ci: bump actions to latest majors (Node 24)

Clears the Node 20 deprecation warnings and the CodeQL Action v3 deprecation:
- actions/checkout v4 -> v6 (all workflows)
- actions/setup-java v4 -> v5
- gradle/actions/setup-gradle v4 -> v6
- actions/upload-artifact v4 -> v7
- github/codeql-action init+analyze v3 -> v4

anthropics/claude-code-action stays at v1 (current major).

Author: devondragon

.github/workflows/build.yml

@@ -13,27 +13,27 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       # Spring Boot 4.x requires Java 21+. The library compiles to Java 21 bytecode via the Gradle
       # toolchain; we additionally verify runtime compatibility on Java 25 (current LTS). Both JDKs are
       # installed; listing 21 last makes it the default JAVA_HOME, so Gradle runs on (and compiles with)
       # Java 21 and discovers Java 25 for the runtime-only testJdk25 task.
       - name: Set up JDK 21 (toolchain) and 25 (runtime)
-        uses: actions/setup-java@v4
+        uses: actions/setup-java@v5
         with:
           distribution: temurin
           java-version: |
             25
             21
       - name: Set up Gradle
-        uses: gradle/actions/setup-gradle@v4
+        uses: gradle/actions/setup-gradle@v6
       - name: Build and test (compile + test on Java 21)
         run: ./gradlew check --no-daemon
       - name: Test on Java 25 (runtime compatibility)
         run: ./gradlew testJdk25 --no-daemon
       - name: Upload test reports
         if: always()
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: test-reports
           path: build/reports/tests/
@@ -43,15 +43,15 @@ jobs:
     permissions:
       security-events: write
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-java@v4
+      - uses: actions/checkout@v6
+      - uses: actions/setup-java@v5
         with:
           distribution: temurin
           java-version: '21'
-      - uses: github/codeql-action/init@v3
+      - uses: github/codeql-action/init@v4
         with:
           languages: java-kotlin
           queries: security-extended
       - name: Build
         run: ./gradlew compileJava --no-daemon
-      - uses: github/codeql-action/analyze@v3
+      - uses: github/codeql-action/analyze@v4

.github/workflows/claude-code-review.yml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 1
 

.github/workflows/claude.yml

@@ -26,7 +26,7 @@ jobs:
       actions: read # Required for Claude to read CI results on PRs
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 1