docs: 整理文档目录结构 — 清理过时文档、归集功能子目录、统一命名规范

清理:
- 删除 34 份过时文档（gap reports/QA临时报告/验收报告/阶段性文档）
- 删除 docs/.hermes/skills 第三方 skills 副本（16 文件）
- 删除 skills-lock.json

目录归集:
- 根目录仅保留 README.md 索引
- product/ — 产品与架构设计（PRD + ARCHITECTURE + P2设计文档 + AI/企业路线图）
- tracking/ — Chatwoot parity 开发跟踪
- requirements/ — M01-M12 模块需求
- plans/ — 历史实现计划
- parity/ — 路由 parity 与前端契约
- qa/ — QA 报告与测试计划
- ops/ — 运维部署

命名规范:
- 全小写 kebab-case，禁止全大写文件名
- product/tracking/ops 用 NN- 序号前缀
- requirements 用 MNN- 两位零填充模块号
- plans/qa 用 YYYY-MM-DD- 日期前缀
- requirements M1-M9 零填充为 M01-M09（修复字典序）

同步更新:
- backend/cmd/route_parity/main.go 路径默认值
- backend/scripts/parity_frontend_smoke.sh 报告路径
- 所有 docs 内部交叉引用
- .gitignore 排除编译产物 (backend/gochat, backend/route_parity)
- 新增迁移 000052/000053
- 前端 WS 相关修改

backend/internal/app/app.go

@@ -257,6 +257,8 @@ func autoMigrate(db *gorm.DB) error {
 		&model.BackgroundJob{},
 		// S6: WorkingHour — out-of-office / business hours per inbox
 		&model.WorkingHour{},
+		// Notification settings — per-user per-account notification preferences
+		&model.NotificationSetting{},
 	}
 
 	for _, m := range models {

backend/internal/app/bootstrap.go

@@ -195,6 +195,7 @@ func Bootstrap(env string) (*App, error) {
 	notificationPrefRepo := repository.NewNotificationPreferenceRepo(db)
 	pushTokenRepo := repository.NewPushTokenRepo(db)
 	notificationSubscriptionRepo := repository.NewNotificationSubscriptionRepo(db)
+	notificationSettingRepo := repository.NewNotificationSettingRepo(db)
 	webhookSubRepo := repository.NewWebhookSubscriptionRepo(db)
 	conversationParticipantRepo := repository.NewConversationParticipantRepo(db)
 	draftMessageRepo := repository.NewDraftMessageRepo(db)
@@ -556,6 +557,7 @@ func Bootstrap(env string) (*App, error) {
 	// P4 Notification+Webhook services
 	pushSubscriptionService := service.NewPushSubscriptionService(pushTokenRepo)
 	notificationSubscriptionService := service.NewNotificationSubscriptionService(notificationSubscriptionRepo)
+	notificationSettingService := service.NewNotificationSettingService(notificationSettingRepo)
 	pushDeliveryService := service.NewPushDeliveryService(pushTokenRepo, cfg.Push.VapidPublicKey, cfg.Push.VapidPrivateKey, cfg.Push.VapidSubject)
 	webhookSubscriptionService := service.NewWebhookSubscriptionService(webhookSubRepo)
 	webhookDeliveryService := service.NewWebhookDeliveryService(webhookSubRepo)
@@ -831,6 +833,7 @@ func Bootstrap(env string) (*App, error) {
 		CannedResponse:           v1.NewCannedResponseHandler(cannedResponseService),
 		PushSubscription:         v1.NewPushSubscriptionHandler(pushSubscriptionService),
 		NotificationSubscription: v1.NewNotificationSubscriptionHandler(notificationSubscriptionService),
+		NotificationSetting:      v1.NewNotificationSettingHandler(notificationSettingService),
 		WebhookSubscription:      v1.NewWebhookSubscriptionHandler(webhookSubscriptionService),
 		TelegramWebhook:          telegramWebhookHandler,
 		FacebookWebhook:          facebookWebhookHandler,