feat:實作通知系統 — 站內通知、Email 通知、Polling 機制

後端
- 新增 6 個 Notification class（預約建立/確認/拒絕/取消/完成、收到評價），database + mail 雙 channel
- 新增 NotificationController（list / unread-count / markRead / markAllRead / destroy）
- 整合通知觸發至 MemberBookingController、ProviderBookingController、CompleteFinishedBookings、ReviewController
- 新增 notifications / jobs / failed_jobs migration
- Docker Compose 加入 queue-worker、mailpit service
- DivingOffer 補上 provider() 關聯

前端
- 新增 notificationStore（Polling 30s/60s 自適應 + Page Visibility API）
- 新增 NotificationBell（未讀 Badge）、NotificationDrawer（側邊通知中心）
- main.js：auth store init 前置於 router.use()，修正 beforeEach guard 時序問題
- notificationAxios：依路徑動態選擇 member/coach token
- NotificationDrawer：改用 new URL().pathname 提取 action_url 路徑

OpenSpec
- 歸檔 notification-system change
- 同步 notification-core / notification-email / notification-triggers specs 至主規格
- 更新 booking-lifecycle / review-lifecycle spec（補充通知觸發 requirement）

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

frontend/src/stores/coachAuth.js

@@ -1,6 +1,7 @@
 import { defineStore } from 'pinia'
 import { ref, computed } from 'vue'
 import coachApi from '../api/coachAxios'
+import { useNotificationStore } from './notifications'
 
 export const useCoachAuthStore = defineStore('coachAuth', () => {
   const user  = ref(null)
@@ -14,6 +15,7 @@ export const useCoachAuthStore = defineStore('coachAuth', () => {
     if (savedToken) {
       token.value = savedToken
       user.value  = savedUser ? JSON.parse(savedUser) : null
+      useNotificationStore().startPolling()
     }
   }
 
@@ -22,12 +24,14 @@ export const useCoachAuthStore = defineStore('coachAuth', () => {
     token.value = tokenValue
     localStorage.setItem('coach_token', tokenValue)
     localStorage.setItem('coach_user', JSON.stringify(userData))
+    useNotificationStore().startPolling()
   }
 
   async function logout() {
     try {
       await coachApi.post('/provider/logout')
     } catch {}
+    useNotificationStore().stopPolling()
     user.value  = null
     token.value = null
     localStorage.removeItem('coach_token')