Refactor to Vue 3 + FastAPI + SQLite architecture

- Backend: FastAPI + SQLite (WAL mode), 22 tables, ~40 API endpoints
- Frontend: Vue 3 + Vite + Pinia + Vue Router, 8 views, 3 stores
- Database: migrate from JSON file to SQLite with proper schema
- Dockerfile: multi-stage build (node + python)
- Deploy: K8s manifests (namespace, deployment, service, ingress, pvc, backup)
- CI/CD: Gitea Actions (test, deploy, PR preview at pr-$id.planner.oci.euphon.net)
- Tests: 20 Cypress E2E test files, 196 test cases, ~85% coverage
- Doc: test-coverage.md with full feature coverage report

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Dockerfile

@@ -1,7 +1,25 @@
-FROM python:3.12-alpine
+FROM node:20-slim AS frontend-build
+
+WORKDIR /build
+COPY frontend/package.json frontend/package-lock.json* ./
+RUN npm install
+COPY frontend/ ./
+RUN npm run build
+
+FROM python:3.12-slim
+
 WORKDIR /app
-COPY server.py .
-COPY index.html sleep-buddy.html favicon.svg icon-180.png notebook.jpg manifest.json sw.js /app/static/
-ENV DATA_DIR=/data STATIC_DIR=/app/static PORT=8080
-EXPOSE 8080
-CMD ["python3", "server.py"]
+
+COPY backend/requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+COPY backend/ ./backend/
+COPY --from=frontend-build /build/dist ./frontend/
+
+ENV DB_PATH=/data/planner.db
+ENV FRONTEND_DIR=/app/frontend
+ENV DATA_DIR=/data
+
+EXPOSE 8000
+
+CMD ["uvicorn", "backend.main:app", "--host", "0.0.0.0", "--port", "8000"]