feat(canvas): 绘图工具 - 集成 Excalidraw 并支持后台切换默认引擎

backend/internal/handler/auth.go

@@ -122,7 +122,12 @@ func RegisterAuthRoutes(r *gin.RouterGroup, svc *service.Service) {
 			failService(c, err)
 			return
 		}
-		ok(c, gin.H{"user": publicUser, "systemChannels": channels, "runtimeLimits": limits})
+		drawingEngine, err := svc.DrawingEngineSetting()
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, gin.H{"user": publicUser, "systemChannels": channels, "runtimeLimits": limits, "drawingEngine": drawingEngine})
 	})
 	r.GET("/channels/system", func(c *gin.Context) {
 		if _, err := currentUser(c, svc); err != nil {
@@ -449,6 +454,37 @@ func RegisterAdminRoutes(r *gin.RouterGroup, svc *service.Service) {
 		}
 		ok(c, gin.H{"setting": setting})
 	})
+	r.GET("/admin/settings/drawing-engine", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		setting, err := svc.AdminDrawingEngineSetting(user)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, gin.H{"setting": setting})
+	})
+	r.PATCH("/admin/settings/drawing-engine", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		var req service.DrawingEngineSetting
+		if err := c.ShouldBindJSON(&req); err != nil {
+			fail(c, http.StatusBadRequest, err)
+			return
+		}
+		setting, err := svc.UpdateDrawingEngineSetting(user, req)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, gin.H{"setting": setting})
+	})
 	r.GET("/admin/settings/runtime-policy", func(c *gin.Context) {
 		user, err := currentUser(c, svc)
 		if err != nil {