feat(workflows): add gate jobs for branch protection in CI, lint, and security workflows

- Introduced `ci-complete`, `lint-complete`, and `security-summary` jobs to aggregate results from respective workflows.
- Each job checks the success of dependent jobs and provides a single status check for branch protection.
- Enhances visibility of CI, linting, and security results, ensuring all checks pass before merging.

.github/workflows/ci.yml

@@ -139,3 +139,27 @@ jobs:
       - name: Build application
         working-directory: apps/frontend
         run: npm run build
+
+  # --------------------------------------------------------------------------
+  # Gate Job - Single check for branch protection
+  # --------------------------------------------------------------------------
+  ci-complete:
+    name: CI Complete
+    runs-on: ubuntu-latest
+    needs: [test-python, test-frontend]
+    if: always()
+    steps:
+      - name: Check all CI jobs passed
+        run: |
+          echo "CI Job Results:"
+          echo "  test-python:   ${{ needs.test-python.result }}"
+          echo "  test-frontend: ${{ needs.test-frontend.result }}"
+          echo ""
+
+          if [[ "${{ needs.test-python.result }}" != "success" ]] || \
+             [[ "${{ needs.test-frontend.result }}" != "success" ]]; then
+            echo "❌ One or more CI jobs failed"
+            exit 1
+          fi
+
+          echo "✅ All CI checks passed"

.github/workflows/lint.yml

@@ -67,3 +67,23 @@ jobs:
         # biome ci fails on errors by default; warnings are reported but don't block
         # Use --error-on-warnings when ready to enforce all rules
         run: biome ci .
+
+  # --------------------------------------------------------------------------
+  # Gate Job - Single check for branch protection
+  # --------------------------------------------------------------------------
+  lint-complete:
+    name: Lint Complete
+    runs-on: ubuntu-latest
+    needs: [python, typescript]
+    if: always()
+    steps:
+      - name: Check lint results
+        run: |
+          if [[ "${{ needs.python.result }}" != "success" ]] || \
+             [[ "${{ needs.typescript.result }}" != "success" ]]; then
+            echo "❌ Linting failed"
+            echo "  Python:     ${{ needs.python.result }}"
+            echo "  TypeScript: ${{ needs.typescript.result }}"
+            exit 1
+          fi
+          echo "✅ All linting passed"

.github/workflows/quality-security.yml

@@ -141,3 +141,41 @@ jobs:
             } else {
               console.log('No high severity security issues found');
             }
+
+  # --------------------------------------------------------------------------
+  # Gate Job - Single check for branch protection
+  # --------------------------------------------------------------------------
+  security-summary:
+    name: Security Summary
+    runs-on: ubuntu-latest
+    needs: [codeql, python-security]
+    if: always()
+    timeout-minutes: 5
+    steps:
+      - name: Check security results
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const codeql = '${{ needs.codeql.result }}';
+            const bandit = '${{ needs.python-security.result }}';
+
+            console.log('Security Check Results:');
+            console.log(`  CodeQL:        ${codeql}`);
+            console.log(`  Bandit:        ${bandit}`);
+
+            // Only 'failure' is a real failure; 'skipped' is acceptable (e.g., path filters, PR skipping CodeQL)
+            const acceptable = ['success', 'skipped'];
+            const codeqlOk = acceptable.includes(codeql);
+            const banditOk = acceptable.includes(bandit);
+            const allPassed = codeqlOk && banditOk;
+
+            if (allPassed) {
+              console.log('\n✅ All security checks passed');
+              core.summary.addRaw('## ✅ Security Checks Passed\n\nAll security scans completed successfully.');
+            } else {
+              console.log('\n❌ Some security checks failed');
+              core.summary.addRaw('## ❌ Security Checks Failed\n\nOne or more security scans found issues.');
+              core.setFailed('Security checks failed');
+            }
+
+            await core.summary.write();