Simplify CI: replace setup-gradle with manual cache + chmod

Remove dependency on gradle/actions/setup-gradle action which may
have version/compatibility issues. Use actions/cache directly for
Gradle caching and explicit chmod +x for the wrapper script.

https://claude.ai/code/session_015LpmjAt17XD582hZ9TPLCv

Author: claude

.github/workflows/ci.yml

@@ -27,8 +27,17 @@ jobs:
           distribution: temurin
           java-version: 17
 
-      - name: Setup Gradle
-        uses: gradle/actions/setup-gradle@v3
+      - name: Cache Gradle
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: gradle-${{ runner.os }}-${{ hashFiles('review-plugin/**/*.gradle*', 'review-plugin/gradle/wrapper/gradle-wrapper.properties') }}
+          restore-keys: gradle-${{ runner.os }}-
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
 
       - name: Build plugin
         run: ./gradlew buildPlugin
@@ -62,8 +71,17 @@ jobs:
           distribution: temurin
           java-version: 17
 
-      - name: Setup Gradle
-        uses: gradle/actions/setup-gradle@v3
+      - name: Cache Gradle
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: gradle-${{ runner.os }}-${{ hashFiles('review-plugin/**/*.gradle*', 'review-plugin/gradle/wrapper/gradle-wrapper.properties') }}
+          restore-keys: gradle-${{ runner.os }}-
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
 
       - name: Verify plugin descriptor
         run: ./gradlew verifyPluginConfiguration