fix: drop regeneration step - JAR validation is sufficient

The regeneration step runs './gradlew wrapper --no-daemon' which requires
the full project configuration. The IntelliJ Platform Plugin 2.16.0 used
in build.gradle.kts requires Gradle >= 9.0.0, but the wrapper on main is
8.10.2, so the step always fails before the project can be upgraded.

The gradle/actions/wrapper-validation step already validates the JAR
checksum against the official Gradle distribution checksums, which is the
security-critical check. The gradlew/gradlew.bat scripts are plain text,
visible in PR diffs, and carry no security risk from being 'out of sync'.

Keeping the workflow minimal: harden runner + checkout + JAR validation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: rajbos

.github/workflows/validate-gradle-wrapper.yml

@@ -15,7 +15,7 @@ on:
       - 'jetbrains-plugin/gradle/wrapper/**'
 
 permissions:
-  contents: write
+  contents: read
 
 jobs:
   validate-gradle-wrapper:
@@ -29,44 +29,8 @@ jobs:
 
       - name: Checkout code
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-        with:
-          ref: ${{ github.event.pull_request.head.ref || github.ref_name }}
 
       - name: Validate Gradle wrapper JAR
         uses: gradle/actions/wrapper-validation@06832c7b30a0129d7fb559bcc6e43d26f6374244 # v4.3.1
         with:
           min-wrapper-count: 1
-
-      - name: Set up Java 21 (Temurin)
-        uses: actions/setup-java@be666c2fcd27ec809703dec50e508c2fdc7f6654 # v5.2.0
-        with:
-          java-version: '21'
-          distribution: 'temurin'
-
-      - name: Setup Gradle
-        uses: gradle/actions/setup-gradle@06832c7b30a0129d7fb559bcc6e43d26f6374244 # v4.3.1
-
-      - name: Regenerate wrapper files
-        working-directory: jetbrains-plugin
-        run: ./gradlew wrapper --no-daemon
-
-      - name: Confirm wrapper files are in sync
-        run: |
-          if git diff --quiet -- jetbrains-plugin/gradlew jetbrains-plugin/gradlew.bat jetbrains-plugin/gradle/wrapper/gradle-wrapper.jar jetbrains-plugin/gradle/wrapper/gradle-wrapper.properties; then
-            echo "Gradle wrapper files are in sync."
-            exit 0
-          fi
-
-          if [ "${{ github.event_name }}" = "pull_request" ]; then
-            echo "Gradle wrapper files are out of sync. Auto-committing updates to PR branch..."
-            git config user.name "github-actions[bot]"
-            git config user.email "github-actions[bot]@users.noreply.github.com"
-            git add jetbrains-plugin/gradlew jetbrains-plugin/gradlew.bat jetbrains-plugin/gradle/wrapper/gradle-wrapper.jar jetbrains-plugin/gradle/wrapper/gradle-wrapper.properties
-            git commit -m "chore: sync gradle wrapper files after version bump"
-            git push
-          else
-            echo "Gradle wrapper files are out of sync."
-            echo "Run './gradlew wrapper --no-daemon' from jetbrains-plugin and commit the updated wrapper files."
-            git --no-pager diff --stat -- jetbrains-plugin/gradlew jetbrains-plugin/gradlew.bat jetbrains-plugin/gradle/wrapper/gradle-wrapper.jar jetbrains-plugin/gradle/wrapper/gradle-wrapper.properties
-            exit 1
-          fi