Centralize CI on SciML reusable workflows

Convert Runic, SpellCheck, and Downgrade to centralized reusable
workflow callers (@v1) with `secrets: "inherit"`. Tests already used
the central caller.

- FormatCheck.yml: inline fredrikekre/runic-action -> runic.yml@v1
- SpellCheck.yml: inline crate-ci/typos -> spellcheck.yml@v1
- Downgrade.yml: inline -> downgrade.yml@v1 (preserve if:false, julia 1.10, skip Pkg,TOML)
- dependabot.yml: drop crate-ci/typos ignore; julia block over dirs with Project.toml (/)

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

@@ -5,13 +5,9 @@ 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:
       - "/"
-      - "/test"
     schedule:
       interval: "daily"
     groups:

.github/workflows/Downgrade.yml

@@ -13,20 +13,8 @@ on:
 jobs:
   test:
     if: false  # Disabled: waiting on dependency updates. See #100 for tracking.
-    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/FormatCheck.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/SpellCheck.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@v1.18.0
+    uses: "SciML/.github/.github/workflows/spellcheck.yml@v1"
+    secrets: "inherit"