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>

deploy/deployment.yaml

@@ -0,0 +1,47 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: planner
+  namespace: planner
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: planner
+  template:
+    metadata:
+      labels:
+        app: planner
+    spec:
+      containers:
+      - name: planner
+        image: planner:latest
+        ports:
+        - containerPort: 8000
+        env:
+        - name: DB_PATH
+          value: /data/planner.db
+        - name: FRONTEND_DIR
+          value: /app/frontend
+        - name: DATA_DIR
+          value: /data
+        volumeMounts:
+        - name: data
+          mountPath: /data
+        resources:
+          requests:
+            memory: "128Mi"
+            cpu: "100m"
+          limits:
+            memory: "256Mi"
+            cpu: "500m"
+        readinessProbe:
+          httpGet:
+            path: /api/backups
+            port: 8000
+          initialDelaySeconds: 5
+          periodSeconds: 10
+      volumes:
+      - name: data
+        persistentVolumeClaim:
+          claimName: planner-data