chore: prepare for edition 2024 by pinning pre-2024 dependencies

Raise MSRV to 1.83 and pin transitive dependencies to versions that
do not require edition 2024, keeping the workspace on edition 2021.
Bump workspace version to 3.1.0-develop.

Cargo.toml:
- rust-version: 1.80 → 1.83
- jsonwebtoken: 10 (rust_crypto) → 9.3
- rand: 0 → 0.9
- Fix LocatedError to v3.0.0

Cargo.lock:
- Downgrade or remove ~30 crates whose latest releases set
  edition 2024 or pull edition-2024 transitive deps (time, clap,
  image, rand, uuid, tera, and others — see ADR-T-003 for the
  full table).

Source:
- rand::RngExt → rand::Rng (renamed in rand 0.9)
- Allow clippy::missing_const_for_fn on map_error_to_image

CI:
- Bump actions/checkout v4 → v6, docker/setup-buildx-action v3 → v4,
  docker/login-action v3 → v4, actions/upload-artifact v4 → v7,
  actions/github-script v7 → v8
- Add MSRV job to testing workflow

ADRs:
- Move docs/adrs/ → adr/ with ADR-T-NNN naming convention
- Rewrite adrs in formal style
- Add ADR-T-003: Preparing for Rust Edition 2024
- Add ADR index to README.md
- Normalise §ADR R-NNN → ADR-R-NNN across render-text-as-image

AGENTS.md:
- Add Test Doc-Headers and cross-reference prefix table
- Clarify atomic file replacement procedure#	modified:   packages/render-text-as-image/adr/001-dependency-selection.md

Author: da2ce7

.github/workflows/container.yaml

@@ -26,7 +26,7 @@ jobs:
     steps:
       - id: setup
         name: Setup Toolchain
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - id: build
         name: Build
@@ -46,7 +46,7 @@ jobs:
 
       - id: checkout
         name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - id: compose
         name: Compose
@@ -117,14 +117,14 @@ jobs:
 
       - id: login
         name: Login to Docker Hub
-        uses: docker/login-action@v3
+        uses: docker/login-action@v4
         with:
           username: ${{ vars.DOCKER_HUB_USERNAME }}
           password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}
 
       - id: setup
         name: Setup Toolchain
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Build and push
         uses: docker/build-push-action@v6
@@ -158,14 +158,14 @@ jobs:
 
       - id: login
         name: Login to Docker Hub
-        uses: docker/login-action@v3
+        uses: docker/login-action@v4
         with:
           username: ${{ vars.DOCKER_HUB_USERNAME }}
           password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}
 
       - id: setup
         name: Setup Toolchain
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
 
       - name: Build and push
         uses: docker/build-push-action@v6

.github/workflows/coverage.yaml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install LLVM tools
         run: sudo apt-get update && sudo apt-get install -y llvm

.github/workflows/deployment.yaml

@@ -17,7 +17,7 @@ jobs:
     steps:
       - id: checkout
         name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - id: setup
         name: Setup Toolchain
@@ -42,7 +42,7 @@ jobs:
     steps:
       - id: checkout
         name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - id: setup
         name: Setup Toolchain

.github/workflows/e2e.yaml

@@ -22,7 +22,7 @@ jobs:
     steps:
       - id: checkout
         name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - id: setup
         name: Setup Toolchain

.github/workflows/generate_coverage_pr.yaml

@@ -19,7 +19,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install LLVM tools
         run: sudo apt-get update && sudo apt-get install -y llvm
@@ -63,13 +63,13 @@ jobs:
       # Triggered sub-workflow is not able to detect the original commit/PR which is available
       # in this workflow.
       - name: Store PR number
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: pr_number
           path: pr_number.txt
 
       - name: Store commit SHA
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: commit_sha
           path: commit_sha.txt
@@ -78,7 +78,7 @@ jobs:
       # is executed by a different workflow `upload_coverage.yml`. The reason for this
       # split is because `on.pull_request` workflows don't have access to secrets.
       - name: Store coverage report in artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: codecov_report
           path: ./codecov.json

.github/workflows/labels.yaml

@@ -25,7 +25,7 @@ jobs:
     steps:
       - id: checkout
         name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - id: sync
         name: Apply Labels from File

.github/workflows/testing.yaml

@@ -15,7 +15,7 @@ jobs:
     steps:
       - id: checkout
         name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - id: setup
         name: Setup Toolchain
@@ -32,6 +32,50 @@ jobs:
         name: Run Formatting-Checks
         run: cargo fmt --check
 
+  msrv:
+    name: MSRV
+    runs-on: ubuntu-latest
+    needs: format
+
+    steps:
+      - id: checkout
+        name: Checkout Repository
+        uses: actions/checkout@v6
+
+      - id: msrv
+        name: Read MSRV from Cargo.toml
+        run: |
+          MSRV=$(sed -n 's/^rust-version = "\(.*\)"/\1/p' Cargo.toml | head -1)
+          echo "version=$MSRV" >> "$GITHUB_OUTPUT"
+
+      - id: setup
+        name: Setup Toolchain
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: ${{ steps.msrv.outputs.version }}
+
+      - id: cache
+        name: Enable Workflow Cache
+        uses: Swatinem/rust-cache@v2
+
+      - id: check
+        name: Run Build Checks
+        run: cargo check --workspace --all-targets --all-features
+
+      - id: imdl
+        name: Install Intermodal
+        run: |
+          rustup install stable
+          cargo +stable install imdl
+
+      - id: test-docs
+        name: Run Documentation Tests
+        run: cargo test --doc
+
+      - id: test
+        name: Run Unit Tests
+        run: cargo test --workspace --all-targets --all-features
+
   check:
     name: Static Analysis
     runs-on: ubuntu-latest
@@ -44,7 +88,7 @@ jobs:
     steps:
       - id: checkout
         name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - id: setup
         name: Setup Toolchain
@@ -97,7 +141,7 @@ jobs:
     steps:
       - id: checkout
         name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - id: setup
         name: Setup Toolchain
@@ -134,7 +178,7 @@ jobs:
     steps:
       - id: checkout
         name: Checkout Repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - id: setup
         name: Setup Toolchain

.github/workflows/upload_coverage_pr.yaml

@@ -22,7 +22,7 @@ jobs:
     steps:
       - name: "Download existing coverage report"
         id: prepare_report
-        uses: actions/github-script@v7
+        uses: actions/github-script@v8
         with:
           script: |
             var fs = require('fs');
@@ -96,7 +96,7 @@ jobs:
           echo "override_commit=$(<commit_sha.txt)" >> "$GITHUB_OUTPUT"
 
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: ${{ steps.parse_previous_artifacts.outputs.override_commit || '' }}
           path: repo_root

AGENTS.md

@@ -34,24 +34,41 @@ API, perhaps using `#[doc(hidden)]` helpers when appropriate.
 | Crate       | `pub(crate)` | `/src/tests/` |
 | Integration | `pub`        | `/tests/`     |
 
+
+## Test Doc-Headers
+
+Every test file (module) should maintain an index of the tests contained in the module-doc. The primary purpose is to make it easy to scan the test files to detect duplicates or overlapping coverage. Please opportunistically create if missing.
+
 ## Cross-Reference Conventions
 
 Eagerly corrected when spotted in **any** file!
 
 Cross-references use the `§` (section sign) prefix. Every reference
-carries a **package qualifier** — `T-` for Torrust —
-so the target document is never ambiguous.
+carries a **package qualifier** so the target document is never ambiguous.
+ADR references (`ADR-T-001`, `ADR-R-001`, …) are an exception — they
+use their own `ADR-<PREFIX>-<NNN>` form without the `§` prefix.
+
+| Prefix | Package              | Example document                     |
+|--------|----------------------|--------------------------------------|
+| `T-`   | Torrust (root crate) | *(none yet)*                         |
+| `R-`   | render-text-as-image | `packages/render-text-as-image/`     |
 
 ### General Rules
 
-- Use `§§` for ranges: e.g. `§§ALGO M-12.2–12.5`.
+- Use `§§` for ranges: e.g. `§§IDEA M-12.2–12.5`.
 - Bare `§N` (no label) is acceptable **within** a document that already
-  establishes context (e.g. inside `algorithm.md` itself), but in source
+  establishes context (e.g. inside `idea.md` itself), but in source
   code and cross-package references always use the fully qualified
   `§BOOK PACKAGE_PREFIX-N` form.
+- Example: `§SPEC R-1.1` refers to §1.1 of `packages/render-text-as-image/docs/specification.md`.
+- ADRs live in an `adr/` directory per package (`/adr/` for the
+  root crate) and use sequential numbering: `NNN-slug.md`. Referenced
+  as `ADR-T-001`, `ADR-R-001`, `ADR-R-002`.
 
 ## Replacing a File
 
+To avoid partial or corrupted writes, always replace files atomically:
+
 1. Read the file.
 2. Using the CLI, `rm` the file.
 3. Recreate the file.