fix: 修复19个Bug (P0-P3) — 持续性调试第7轮发现的问题

P0 (5): crypto/rand session ID, TTS fallback可达性, goroutine defer recover, adminAuth前缀修正
P1 (5): 普通用户密码验证, context传递, priority clamp, 超时重试, 自主思考速率限制
P2 (4): Briefing AI降级, 前端消息类型渲染, Docker Compose补全, PWA 192图标
P3 (5): goroutine错误处理, .gitignore完善, reminder created_at, voice Dockerfile, Go版本更新

backend/gateway/cmd/main.go

@@ -124,7 +124,11 @@ func main() {
     hub.StartIoTBroadcast(cfg.IoTDebugServiceURL)
 
     // 注册路由
-    router.Setup(r, hub, cfg, sessionStore, reminderStore, briefingStore, automationStore, fileStore, ruleEngine, knowledgeStore, nil)
+    var db interface{}
+    if sessionStore != nil {
+    	db = sessionStore.DB()
+    }
+    router.Setup(r, hub, cfg, sessionStore, reminderStore, briefingStore, automationStore, fileStore, ruleEngine, knowledgeStore, nil, db)
    
     // 启动提醒调度器
     if reminderStore != nil {