chore: pin actions to commit SHAs and add Skills section to CLAUDE.md

Pin all GitHub Actions to commit SHAs instead of mutable version tags
across ci.yml, release.yml, maintenance.yml, and all reusable workflows.
This prevents supply-chain attacks via tag hijacking.

Add the required Skills section to CLAUDE.md mapping project files
(README.md, .github/workflows/*.yml) to their respective review skills.

.github/workflows/ci.yml

@@ -34,10 +34,10 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - name: Setup Node.js ${{ matrix.node }}
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
         with:
           node-version: ${{ matrix.node }}
 
@@ -68,7 +68,7 @@ jobs:
 
       - name: Cache npm
         if: matrix.pm == 'npm'
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ${{ steps.npm-cache-dir.outputs.dir }}
           key: ${{ runner.os }}-node-${{ matrix.node }}-npm-${{ hashFiles('**/package-lock.json') }}
@@ -83,7 +83,7 @@ jobs:
 
       - name: Cache pnpm
         if: matrix.pm == 'pnpm'
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ${{ steps.pnpm-cache-dir.outputs.dir }}
           key: ${{ runner.os }}-node-${{ matrix.node }}-pnpm-${{ hashFiles('**/pnpm-lock.yaml') }}
@@ -104,7 +104,7 @@ jobs:
 
       - name: Cache yarn
         if: matrix.pm == 'yarn'
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ${{ steps.yarn-cache-dir.outputs.dir }}
           key: ${{ runner.os }}-node-${{ matrix.node }}-yarn-${{ hashFiles('**/yarn.lock') }}
@@ -113,7 +113,7 @@ jobs:
 
       - name: Cache bun
         if: matrix.pm == 'bun'
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ~/.bun/install/cache
           key: ${{ runner.os }}-bun-${{ hashFiles('**/bun.lockb') }}
@@ -146,7 +146,7 @@ jobs:
       # Upload test artifacts on failure
       - name: Upload test artifacts
         if: failure()
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: test-results-${{ matrix.os }}-node${{ matrix.node }}-${{ matrix.pm }}
           path: |
@@ -160,10 +160,10 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
         with:
           node-version: '20.x'
 
@@ -205,10 +205,10 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
         with:
           node-version: '20.x'
 
@@ -223,10 +223,10 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
         with:
           node-version: '20.x'
 

.github/workflows/maintenance.yml

@@ -15,8 +15,8 @@ jobs:
     name: Check Dependencies
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
         with:
           node-version: '20.x'
       - name: Check for outdated packages
@@ -26,8 +26,8 @@ jobs:
     name: Security Audit
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
         with:
           node-version: '20.x'
       - name: Run security audit
@@ -43,7 +43,7 @@ jobs:
     name: Stale Issues/PRs
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/stale@v9
+      - uses: actions/stale@5bef64f19d7facfb25b37b414482c7164d639639 # v9
         with:
           stale-issue-message: 'This issue is stale due to inactivity.'
           stale-pr-message: 'This PR is stale due to inactivity.'

.github/workflows/release.yml

@@ -14,7 +14,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
         with:
           fetch-depth: 0
 

.github/workflows/reusable-release.yml

@@ -23,7 +23,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
         with:
           fetch-depth: 0
 

.github/workflows/reusable-test.yml

@@ -27,10 +27,10 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
         with:
           node-version: ${{ inputs.node-version }}
 
@@ -59,7 +59,7 @@ jobs:
 
       - name: Cache npm
         if: inputs.package-manager == 'npm'
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ${{ steps.npm-cache-dir.outputs.dir }}
           key: ${{ runner.os }}-node-${{ inputs.node-version }}-npm-${{ hashFiles('**/package-lock.json') }}
@@ -74,7 +74,7 @@ jobs:
 
       - name: Cache pnpm
         if: inputs.package-manager == 'pnpm'
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ${{ steps.pnpm-cache-dir.outputs.dir }}
           key: ${{ runner.os }}-node-${{ inputs.node-version }}-pnpm-${{ hashFiles('**/pnpm-lock.yaml') }}
@@ -95,7 +95,7 @@ jobs:
 
       - name: Cache yarn
         if: inputs.package-manager == 'yarn'
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ${{ steps.yarn-cache-dir.outputs.dir }}
           key: ${{ runner.os }}-node-${{ inputs.node-version }}-yarn-${{ hashFiles('**/yarn.lock') }}
@@ -104,7 +104,7 @@ jobs:
 
       - name: Cache bun
         if: inputs.package-manager == 'bun'
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ~/.bun/install/cache
           key: ${{ runner.os }}-bun-${{ hashFiles('**/bun.lockb') }}
@@ -134,7 +134,7 @@ jobs:
 
       - name: Upload test artifacts
         if: failure()
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: test-results-${{ inputs.os }}-node${{ inputs.node-version }}-${{ inputs.package-manager }}
           path: |

.github/workflows/reusable-validate.yml

@@ -17,10 +17,10 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
         with:
           node-version: ${{ inputs.node-version }}