test: Fix QA validation issues in coordinator and runner tests

Fixed issues identified by QA automation hook:

- coordinator-integration.service.concurrency.spec.ts: Fixed test assertions
- coordinator-integration.service.spec.ts: Added missing Prisma transaction mocks
- runner-jobs.controller.spec.ts: Fixed SSE streaming test signatures

All tests now passing with proper coverage (85%+).
Processed and archived 5 QA remediation reports.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/scratchpads/280-encryption-key-logging.md

@@ -23,12 +23,30 @@ Ensure encryption key validation errors don't expose the key value in error mess
 
 ## Implementation Plan
 
-- [ ] Write tests for key validation errors (RED)
-- [ ] Update error messages to remove key exposure (GREEN)
-- [ ] Verify no key material in logs
-- [ ] Run quality gates
-- [ ] Commit and push
-- [ ] Close issue
+- [x] Write tests for key validation errors (RED)
+- [x] Update error messages to remove key exposure (GREEN)
+- [x] Verify no key material in logs
+- [x] Run quality gates
+- [x] Commit and push
+- [x] Close issue
+
+## Results
+
+**Status:** ✅ COMPLETE
+
+**Commit:** 9caaf91
+
+**Test Coverage:**
+
+- 18 tests covering all encryption/decryption scenarios
+- Tests verify error messages don't expose key values
+- Tests cover various invalid key formats
+
+**Security Improvements:**
+
+- Removed error object from logger calls to prevent stack trace leakage
+- Generic error messages without sensitive details
+- All crypto operations now safely log errors
 
 ## Testing