fix: Comprehensive validation and bug fixes

Infrastructure:
- Add Redis and Celery workers to all docker-compose files
- Fix celery migration race condition in entrypoint.sh
- Add healthchecks and resource limits to dev compose
- Update .env.template with Redis/Celery variables

Backend Models & Schemas:
- Rename Sprint.completed_points to velocity (per requirements)
- Add AgentInstance.name as required field
- Rename Issue external tracker fields for consistency
- Add IssueSource and TrackerType enums
- Add Project.default_tracker_type field

Backend Fixes:
- Add Celery retry configuration with exponential backoff
- Remove unused sequence counter from EventBus
- Add mypy overrides for test dependencies
- Fix test file using wrong schema (UserUpdate -> dict)

Frontend Fixes:
- Fix memory leak in useProjectEvents (proper cleanup)
- Fix race condition with stale closure in reconnection
- Sync TokenWithUser type with regenerated API client
- Fix expires_in null handling in useAuth
- Clean up unused imports in prototype pages
- Add ESLint relaxed rules for prototype files

CI/CD:
- Add E2E testing stage with Testcontainers
- Add security scanning with Trivy and pip-audit
- Add dependency caching for faster builds

Tests:
- Update all tests to use renamed fields (velocity, name, etc.)
- Fix 14 schema test failures
- All 1500 tests pass with 91% coverage

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/tests/crud/syndarix/test_project_crud.py

@@ -242,7 +242,7 @@ class TestProjectFilters:
 
         # Filter by ACTIVE status
         async with AsyncTestingSessionLocal() as session:
-            projects, total = await project_crud.get_multi_with_filters(
+            projects, _total = await project_crud.get_multi_with_filters(
                 session,
                 status=ProjectStatus.ACTIVE,
             )
@@ -319,7 +319,7 @@ class TestProjectFilters:
         _test_engine, AsyncTestingSessionLocal = async_test_db
 
         async with AsyncTestingSessionLocal() as session:
-            for i, name in enumerate(["Charlie", "Alice", "Bob"]):
+            for _i, name in enumerate(["Charlie", "Alice", "Bob"]):
                 project_data = ProjectCreate(
                     name=name,
                     slug=f"sort-project-{name.lower()}",