feat: Phase 6.3 - 注册 Session REST 路由，统一依赖注入

backend/cmd/server/main.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/gin-gonic/gin"
 
+	"github.com/hhs/camtalk/internal/api"
 	"github.com/hhs/camtalk/internal/ai/llm"
 	"github.com/hhs/camtalk/internal/ai/stt"
 	"github.com/hhs/camtalk/internal/ai/tts"
@@ -61,11 +62,15 @@ func main() {
 	r.Use(gin.Recovery())
 
 	// REST API
-	api := r.Group("/api")
+	apiGroup := r.Group("/api")
 	{
-		api.GET("/health", healthHandler(sessionMgr))
+		apiGroup.GET("/health", healthHandler(sessionMgr))
 	}
 
+	// Session REST 端点
+	sessionHandler := api.NewSessionHandler(sessionMgr)
+	sessionHandler.RegisterRoutes(apiGroup)
+
 	// WebSocket
 	r.GET("/ws", ws.ServeWS(sessionMgr, orch))