fix: resolve all MyPy type errors and add poetry.lock for reproducible builds

- Install missing type stubs (types-PyYAML, celery-types, types-redis)
- Fix template_generator.py: add explicit type casts for YAML data
- Fix documentation_tasks.py: add Task type hints for Celery decorators
- Fix api/main.py: add type annotations for AsyncResult and response dicts
- Fix chat/main.py: add type ignore for socketio (no stubs available)
- Remove poetry.lock from .gitignore (needed for Docker builds)
- Add poetry.lock to ensure reproducible dependency installation
- Format code with Black and verify with Ruff

All MyPy checks now pass: 18 errors → 0 errors

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

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

pyproject.toml

@@ -90,6 +90,9 @@ mypy = "^1.13.0"
 pre-commit = "^4.0.0"
 ipython = "^8.30.0"
 bandit = "^1.8.6"
+types-pyyaml = "^6.0.12.20250915"
+celery-types = "^0.23.0"
+types-redis = "^4.6.0.20241004"
 
 [tool.poetry.scripts]
 datacenter-docs = "datacenter_docs.cli:app"