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>

docker-compose.yml

@@ -0,0 +1,11 @@
+services:
+  app:
+    build: .
+    image: habit-tracker:latest
+    restart: unless-stopped
+    ports:
+      - "8000:8000"
+    environment:
+      - TZ=Asia/Seoul
+    env_file:
+      - .env