Centralize CI to use SciML reusable workflows

Convert all CI workflows to the centralized SciML/.github reusable
workflows (@v1) with `secrets: "inherit"`:

- Documentation: inline build/deploy -> documentation.yml@v1
- FormatCheck (Runic): inline runic-action -> runic.yml@v1
- SpellCheck (typos): inline crate-ci/typos -> spellcheck.yml@v1
- Downgrade: inline -> downgrade.yml@v1 (preserve `if: false` disable
  and julia-version 1.10, skip Pkg,TOML)
- Tests: already a tests.yml@v1 caller (unchanged)

Cleanup:
- Delete CompatHelper.yml (handled centrally / by dependabot)
- dependabot.yml: drop crate-ci/typos ignore, add julia ecosystem block
  over /, /docs, /test (daily, grouped all-julia-packages)

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: ChrisRackauckas

.github/dependabot.yml

@@ -5,6 +5,14 @@ updates:
     directory: "/" # Location of package manifests
     schedule:
       interval: "weekly"
-    ignore:
-      - dependency-name: "crate-ci/typos"
-        update-types: ["version-update:semver-patch", "version-update:semver-minor"]
+  - package-ecosystem: "julia"
+    directories:
+      - "/"
+      - "/docs"
+      - "/test"
+    schedule:
+      interval: "daily"
+    groups:
+      all-julia-packages:
+        patterns:
+          - "*"

.github/workflows/CompatHelper.yml

@@ -13,20 +13,8 @@ on:
 jobs:
   test:
     if: false  # Disabled pending dependency updates - see issue #142
-    runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        downgrade_mode: ['alldeps']
-        julia-version: ['1.10']
-    steps:
-      - uses: actions/checkout@v6
-      - uses: julia-actions/setup-julia@v3
-        with:
-          version: ${{ matrix.julia-version }}
-      - uses: julia-actions/julia-downgrade-compat@v2
-        with:
-          skip: Pkg,TOML
-      - uses: julia-actions/julia-buildpkg@v1
-      - uses: julia-actions/julia-runtest@v1
-        with:
-          ALLOW_RERESOLVE: false
+    uses: "SciML/.github/.github/workflows/downgrade.yml@v1"
+    with:
+      julia-version: "1.10"
+      skip: "Pkg,TOML"
+    secrets: "inherit"

.github/workflows/Downgrade.yml

@@ -11,12 +11,5 @@ on:
 
 jobs:
   runic:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v6
-      - uses: julia-actions/setup-julia@v3
-        with:
-          version: '1'
-      - uses: fredrikekre/runic-action@v1
-        with:
-          version: '1'
+    uses: "SciML/.github/.github/workflows/runic.yml@v1"
+    secrets: "inherit"

.github/workflows/FormatCheck.yml

@@ -4,10 +4,5 @@ on: [pull_request]
 
 jobs:
   typos-check:
-    name: Spell Check with Typos
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout Actions Repository
-        uses: actions/checkout@v6
-      - name: Check spelling
-        uses: crate-ci/typos@v1.35.3 
+    uses: "SciML/.github/.github/workflows/spellcheck.yml@v1"
+    secrets: "inherit"

.github/workflows/SpellCheck.yml

@@ -9,23 +9,5 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v6
-      - uses: julia-actions/setup-julia@latest
-        with:
-          version: '1'
-      - name: Install dependencies
-        run: julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate()'
-      - name: Build and deploy
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} # For authentication with GitHub Actions token
-          DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }} # For authentication with SSH deploy key
-          GKSwstype: "100" # no output on headless systems
-        run: julia --project=docs/ --code-coverage=user docs/make.jl
-      - uses: julia-actions/julia-processcoverage@v1
-      - uses: codecov/codecov-action@v6
-        with:
-          files: lcov.info
-          token: ${{ secrets.CODECOV_TOKEN }}
-          fail_ci_if_error: true
+    uses: "SciML/.github/.github/workflows/documentation.yml@v1"
+    secrets: "inherit"