Initial commit: habit tracker PWA with Google OAuth, push notifications

FastAPI + SQLAlchemy/Alembic + MariaDB backend with Jinja2/htmx/Alpine
server-rendered frontend. Multi-user via Google OAuth, daily habit
tracking, monthly/weekly history views, Web Push reminders via
APScheduler, and PWA support (manifest, service worker, offline caching).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,14 @@
+__pycache__/
+*.pyc
+.env
+.env.dev
+.venv/
+venv/
+*.egg-info/
+.pytest_cache/
+.idea/
+*.iml
+node_modules/
+logs/
+img*.png
+image.md