feat: production docker + documentation

- Backend Dockerfile: multi-stage build with venv, gunicorn+uvicorn workers, entrypoint runs alembic then gunicorn
- Frontend Dockerfile: multi-stage with npm ci, nginx:1.27-alpine runtime
- nginx.conf: gzip compression, security headers (X-Frame-Options, X-Content-Type-Options, etc.), static asset caching, correct API proxy preserving /api/ prefix
- docker-compose.yml: production config — db healthcheck, backend healthcheck, frontend depends_on backend healthy, no exposed backend port
- docker-compose.override.yml: dev hot-reload — uvicorn --reload with source mount, npm run dev on port 5173
- Rate limiting: slowapi middleware on /auth/login (10/min) and /auth/register (5/min)
- README.md: full documentation with architecture, quick start, API table, dev/prod instructions, tests
- .env.example: all variables documented with comments
- .gitignore: extended with *.pyc, *.cover, .ruff_cache, frontend/.vite, etc.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -1,32 +1,45 @@
 # Python
 __pycache__/
 *.py[cod]
+*.pyc
+*.pyo
 *.egg-info/
-dist/
 .venv/
 venv/
+*.cover
+.coverage
+htmlcov/
+.pytest_cache/
+.ruff_cache/
+*.egg
 
 # Node
 node_modules/
 frontend/dist/
+frontend/.vite/
+*.tsbuildinfo
 
-# Environment
+# Environment — never commit secrets
 .env
+.env.local
+.env.*.local
 
 # IDE
 .vscode/
 .idea/
 *.swp
 *.swo
+*.sublime-project
+*.sublime-workspace
 
 # OS
 .DS_Store
 Thumbs.db
+desktop.ini
 
 # Docker
 pgdata/
 
-# Testing
-.coverage
-htmlcov/
-.pytest_cache/
+# Build artifacts
+dist/
+build/