fix: 移除早间简报功能 + 修复多处"人机感"用语

- 删除 briefing_handler.go / briefing_store.go 及所有相关路由与配置
- 移除 Gateway Config 中 ToolEngineURL / BriefingTime 字段
- 移除 DevTools 中 gateway 的 TOOL_ENGINE_URL 环境变量
- webhook 错误提示从"AI 服务异常/暂不可用"改为昔涟自然口吻
- markdown 导出中昔涟头像从 🤖 改为 💫
- 后台思考提示词"系统会误解析"改为"我会误解析"

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/gateway/internal/router/router.go

@@ -15,7 +15,7 @@ import (
 )
 
 // Setup 注册所有路由
-func Setup(r *gin.Engine, hub *ws.Hub, cfg *config.Config, sessionStore *store.SessionStore, reminderStore *store.ReminderStore, briefingStore *store.BriefingStore, automationStore *store.AutomationStore, fileStore *store.FileStore, ruleEngine *engine.RuleEngine, knowledgeStore *store.KnowledgeStore, imageHandler *handler.ImageHandler, db interface{}, modelConfigStore *config.ModelsConfigStore, thinkingScheduleStore *config.ThinkingScheduleStore) {
+func Setup(r *gin.Engine, hub *ws.Hub, cfg *config.Config, sessionStore *store.SessionStore, reminderStore *store.ReminderStore, automationStore *store.AutomationStore, fileStore *store.FileStore, ruleEngine *engine.RuleEngine, knowledgeStore *store.KnowledgeStore, imageHandler *handler.ImageHandler, db interface{}, modelConfigStore *config.ModelsConfigStore, thinkingScheduleStore *config.ThinkingScheduleStore) {
 	// 限流器
 	rateLimiter := middleware.NewRateLimiter(10, 20) // 每秒10个请求，突发20
 
@@ -31,7 +31,6 @@ func Setup(r *gin.Engine, hub *ws.Hub, cfg *config.Config, sessionStore *store.S
 	webhookHandler := handler.NewWebhookHandler(cfg, hub)
 	notificationHandler := handler.NewNotificationHandler(cfg, hub)
 	reminderHandler := handler.NewReminderHandler(reminderStore, hub)
-	briefingHandler := handler.NewBriefingHandler(cfg, hub, briefingStore, reminderStore)
 	voiceHandler := handler.NewVoiceHandler(cfg.VoiceServiceURL)
 	fileHandler := handler.NewFileHandler(fileStore)
 	automationHandler := handler.NewAutomationHandler(automationStore, ruleEngine)
@@ -115,14 +114,6 @@ func Setup(r *gin.Engine, hub *ws.Hub, cfg *config.Config, sessionStore *store.S
 			reminders.DELETE("/:id", reminderHandler.Delete)  // DELETE /api/v1/reminders/:id
 		}
 
-		// 每日简报 (需要认证)
-		briefings := protected.Group("/briefings")
-		{
-			briefings.GET("", briefingHandler.GetBriefing)             // GET  /api/v1/briefings?user_id=xxx&date=2024-01-01
-			briefings.GET("/latest", briefingHandler.GetLatestBriefings) // GET  /api/v1/briefings/latest?user_id=xxx&limit=7
-			briefings.POST("/generate", briefingHandler.Generate)       // POST /api/v1/briefings/generate
-		}
-
 		// 语音识别 + TTS (需要认证)
 		voice := protected.Group("/voice")
 		{