feat(metrics): Implement scan metrics repository and PostgreSQL integration

- Added IScanMetricsRepository interface for scan metrics persistence and retrieval.
- Implemented PostgresScanMetricsRepository for PostgreSQL database interactions, including methods for saving and retrieving scan metrics and execution phases.
- Introduced methods for obtaining TTE statistics and recent scans for tenants.
- Implemented deletion of old metrics for retention purposes.

test(tests): Add SCA Failure Catalogue tests for FC6-FC10

- Created ScaCatalogueDeterminismTests to validate determinism properties of SCA Failure Catalogue fixtures.
- Developed ScaFailureCatalogueTests to ensure correct handling of specific failure modes in the scanner.
- Included tests for manifest validation, file existence, and expected findings across multiple failure cases.

feat(telemetry): Integrate scan completion metrics into the pipeline

- Introduced IScanCompletionMetricsIntegration interface and ScanCompletionMetricsIntegration class to record metrics upon scan completion.
- Implemented proof coverage and TTE metrics recording with logging for scan completion summaries.

.gitea/workflows/build-test-deploy.yml

@@ -575,6 +575,71 @@ PY
           if-no-files-found: ignore
           retention-days: 7
 
+  # ============================================================================
+  # Quality Gates Foundation (Sprint 0350)
+  # ============================================================================
+  quality-gates:
+    runs-on: ubuntu-22.04
+    needs: build-test
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Reachability quality gate
+        id: reachability
+        run: |
+          set -euo pipefail
+          echo "::group::Computing reachability metrics"
+          if [ -f scripts/ci/compute-reachability-metrics.sh ]; then
+            chmod +x scripts/ci/compute-reachability-metrics.sh
+            METRICS=$(./scripts/ci/compute-reachability-metrics.sh --dry-run 2>/dev/null || echo '{}')
+            echo "metrics=$METRICS" >> $GITHUB_OUTPUT
+            echo "Reachability metrics: $METRICS"
+          else
+            echo "Reachability script not found, skipping"
+          fi
+          echo "::endgroup::"
+
+      - name: TTFS regression gate
+        id: ttfs
+        run: |
+          set -euo pipefail
+          echo "::group::Computing TTFS metrics"
+          if [ -f scripts/ci/compute-ttfs-metrics.sh ]; then
+            chmod +x scripts/ci/compute-ttfs-metrics.sh
+            METRICS=$(./scripts/ci/compute-ttfs-metrics.sh --dry-run 2>/dev/null || echo '{}')
+            echo "metrics=$METRICS" >> $GITHUB_OUTPUT
+            echo "TTFS metrics: $METRICS"
+          else
+            echo "TTFS script not found, skipping"
+          fi
+          echo "::endgroup::"
+
+      - name: Performance SLO gate
+        id: slo
+        run: |
+          set -euo pipefail
+          echo "::group::Enforcing performance SLOs"
+          if [ -f scripts/ci/enforce-performance-slos.sh ]; then
+            chmod +x scripts/ci/enforce-performance-slos.sh
+            ./scripts/ci/enforce-performance-slos.sh --warn-only || true
+          else
+            echo "Performance SLO script not found, skipping"
+          fi
+          echo "::endgroup::"
+
+      - name: Upload quality gate results
+        uses: actions/upload-artifact@v4
+        with:
+          name: quality-gate-results
+          path: |
+            scripts/ci/*.json
+            scripts/ci/*.yaml
+          if-no-files-found: ignore
+          retention-days: 14
+
   sealed-mode-ci:
     runs-on: ubuntu-22.04
     needs: build-test