feat(ci): replace integration lane with runtime black-box tests

docs/CICD_SUCCESS_SUMMARY.md

@@ -33,6 +33,8 @@
 - **E2E Tests**: Simplified Docker approach matching other successful test patterns
 - **Playwright**: Chromium-only CI strategy (95%+ browser market coverage)
 - **Registry Operations**: Consistent approach across all test phases
+- **Backend Runtime Integration**: Black-box checks run against started deployable
+  backend containers with commit-tag and digest pinning
 
 ## 🛠️ **Critical Issues Resolved**
 
@@ -82,6 +84,8 @@ Frontend Environment (Yarn PnP)
     ↓ (state regeneration)
 Test Execution (all phases)
     ↓ (consistent Docker approach)
+Runtime Black-Box Integration
+    ↓ (deployable backend tag+digest verification)
 E2E Testing (Playwright)
     ↓ (Chromium + network resilience)
 ✅ SUCCESS

docs/DEPLOYABLE_RUNTIME_CONTRACT.md

@@ -157,6 +157,12 @@ Current enforcement implemented in CI:
   - Workflow: `.gitea/workflows/docker-build-main.yaml`
   - Checks include binary presence and profile-specific package metadata probes
     to detect CI/development tooling leakage.
+- Runtime black-box integration checks against deployed backend container:
+  - Workflow: `.gitea/workflows/cicd-tests.yaml` (`integration-tests` job)
+  - Inputs: deployable backend commit tag reference and immutable digest
+    reference from main build dispatch.
+  - Assertions: digest/tag consistency and live endpoint behavior for `/`,
+    `/compatibility`, and `/health` on started runtime containers.
 
 Future follow-up automation under epic #66 may expand this with: