ci: upgrade GitHub Actions to Node.js 24-compatible versions

Update shared workflow action versions ahead of the June 2, 2026 deadline
when GitHub forces all actions from Node.js 20 to Node.js 24:

- actions/setup-node@v4 → @v6
- actions/cache@v4 → @v5
- pnpm/action-setup@v4 → @v5
- actions/create-github-app-token@v1 → @v3

Affects: plugin-ci.yaml, plugin-release.yaml, ci-health-check.yaml

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.github/workflows/ci-health-check.yaml

@@ -14,7 +14,7 @@ jobs:
 
       - name: Generate GitHub App token
         id: app-token
-        uses: actions/create-github-app-token@v1
+        uses: actions/create-github-app-token@v3
         continue-on-error: true
         with:
           app-id: ${{ secrets.RELEASE_APP_ID }}

.github/workflows/plugin-ci.yaml

@@ -36,7 +36,7 @@ jobs:
           fi
 
       - name: Setup Node
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: ${{ inputs.node-version }}
           # Only enable built-in npm caching here; pnpm caching is handled below
@@ -51,7 +51,7 @@ jobs:
 
       - name: Setup pnpm (version latest)
         if: steps.pkg-manager.outputs.manager == 'pnpm' && steps.pkg-manager.outputs.has_package_manager == 'false'
-        uses: pnpm/action-setup@v4
+        uses: pnpm/action-setup@v5
         with:
           run_install: false
           version: latest
@@ -63,7 +63,7 @@ jobs:
 
       - name: Cache pnpm store
         if: steps.pkg-manager.outputs.manager == 'pnpm'
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ${{ steps.pnpm-store.outputs.dir }}
           key: ${{ runner.os }}-pnpm-${{ hashFiles('**/pnpm-lock.yaml') }}

.github/workflows/plugin-release.yaml

@@ -110,12 +110,12 @@ jobs:
 
       - name: Setup pnpm
         if: steps.pkg-manager.outputs.manager == 'pnpm'
-        uses: pnpm/action-setup@v4
+        uses: pnpm/action-setup@v5
         with:
           run_install: false
 
       - name: Setup Node
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@v6
         with:
           node-version: ${{ inputs.node-version }}
           cache: ${{ steps.pkg-manager.outputs.manager }}
@@ -219,7 +219,7 @@ jobs:
 
       - name: Generate GitHub App token
         id: app-token
-        uses: actions/create-github-app-token@v1
+        uses: actions/create-github-app-token@v3
         with:
           app-id: ${{ secrets.RELEASE_APP_ID }}
           private-key: ${{ secrets.RELEASE_APP_PRIVATE_KEY }}