feat(welcome): 站点外观 - 合并欢迎页开放开关与入口分包修复

# Conflicts:
#	docs/content/docs/progress/pending-test.mdx

backend/internal/handler/feature_availability.go

@@ -9,6 +9,16 @@ import (
 )
 
 func RegisterFeatureAvailabilityRoutes(r *gin.RouterGroup, svc *service.Service) {
+	r.GET("/public/welcome", func(c *gin.Context) {
+		c.Header("Cache-Control", "no-store")
+		setting, err := svc.FeatureAvailability()
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, gin.H{"welcomeEnabled": setting.WelcomeEnabled})
+	})
+
 	r.GET("/features", func(c *gin.Context) {
 		if _, err := currentUser(c, svc); err != nil {
 			failService(c, err)

backend/internal/handler/openapi.yaml

@@ -24,6 +24,16 @@ tags:
   - name: agent
   - name: admin
 paths:
+  /public/welcome:
+    get:
+      tags: [meta]
+      security: []
+      summary: 读取欢迎页开放状态
+      responses:
+        "200":
+          description: 信封 data 仅包含 welcomeEnabled 布尔值，默认 true；Cache-Control 为 no-store
+        "500":
+          description: 配置读取失败
   /agent/capabilities:
     get:
       tags: [agent]

backend/internal/handler/welcome_routes_test.go

@@ -0,0 +1,56 @@
+package handler
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"infinite-canvas/backend/internal/model"
+	"infinite-canvas/backend/internal/repository"
+	"infinite-canvas/backend/internal/service"
+
+	"github.com/gin-gonic/gin"
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+)
+
+func TestWelcomeAvailabilityPublicRoute(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	db, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	sqlDB, err := db.DB()
+	if err != nil {
+		t.Fatal(err)
+	}
+	sqlDB.SetMaxOpenConns(1)
+	t.Cleanup(func() { _ = sqlDB.Close() })
+	if err := db.AutoMigrate(&model.SystemSetting{}); err != nil {
+		t.Fatal(err)
+	}
+	router := gin.New()
+	RegisterFeatureAvailabilityRoutes(router.Group("/api"), service.New(repository.New(db), t.TempDir()))
+	for _, enabled := range []bool{true, false, true} {
+		payload, _ := json.Marshal(map[string]bool{"welcomeEnabled": enabled})
+		if err := db.Save(&model.SystemSetting{Key: "feature_availability", ValueJSON: string(payload)}).Error; err != nil {
+			t.Fatal(err)
+		}
+		response := httptest.NewRecorder()
+		router.ServeHTTP(response, httptest.NewRequest(http.MethodGet, "/api/public/welcome", nil))
+		if response.Code != http.StatusOK || response.Header().Get("Cache-Control") != "no-store" {
+			t.Fatalf("unexpected public response: %d %s", response.Code, response.Body.String())
+		}
+		var body struct {
+			Code int             `json:"code"`
+			Data map[string]bool `json:"data"`
+		}
+		if err := json.Unmarshal(response.Body.Bytes(), &body); err != nil {
+			t.Fatal(err)
+		}
+		if body.Code != 0 || len(body.Data) != 1 || body.Data["welcomeEnabled"] != enabled {
+			t.Fatalf("unexpected public payload: %s", response.Body.String())
+		}
+	}
+}