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>

frontend/src/stores/auth.js

@@ -0,0 +1,42 @@
+import { defineStore } from 'pinia'
+import { ref, computed } from 'vue'
+import { api } from '../composables/useApi'
+
+export const useAuthStore = defineStore('auth', () => {
+  const loggedIn = ref(false)
+
+  function checkLogin() {
+    const exp = localStorage.getItem('sp_login_expires')
+    loggedIn.value = exp && Date.now() < parseInt(exp)
+    return loggedIn.value
+  }
+
+  async function login(password) {
+    const buf = await crypto.subtle.digest('SHA-256', new TextEncoder().encode(password))
+    const hash = Array.from(new Uint8Array(buf)).map(b => b.toString(16).padStart(2, '0')).join('')
+    await api.post('/api/login', { hash })
+    localStorage.setItem('sp_login_expires', String(Date.now() + 7 * 86400000))
+    loggedIn.value = true
+  }
+
+  function logout() {
+    localStorage.removeItem('sp_login_expires')
+    loggedIn.value = false
+  }
+
+  async function changePassword(oldPass, newPass) {
+    const hash = async (s) => {
+      const buf = await crypto.subtle.digest('SHA-256', new TextEncoder().encode(s))
+      return Array.from(new Uint8Array(buf)).map(b => b.toString(16).padStart(2, '0')).join('')
+    }
+    await api.post('/api/change-password', {
+      oldHash: await hash(oldPass),
+      newHash: await hash(newPass),
+    })
+  }
+
+  // Auto-check on init
+  checkLogin()
+
+  return { loggedIn, checkLogin, login, logout, changePassword }
+})