feat: add brand asset upload with PNG conversion and improve config validation

- Add file upload support for logo and favicon with automatic PNG conversion
- Add backend validation for brand asset data URLs (app_logo, app_favicon)
- Change vite_config.value column type from varchar(200) to text for PostgreSQL
- Add schema migration v3 for vite_config.value column type conversion
- Update frontend to use file picker instead of manual URL input
- Add early favicon application in index.html to prevent flash

go-backend/internal/http/handler/handler.go

@@ -3,6 +3,7 @@ package handler
 import (
 	"context"
 	"database/sql"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -72,6 +73,11 @@ type flowItem struct {
 	D int64  `json:"d"`
 }
 
+const (
+	pngDataURLPrefix          = "data:image/png;base64,"
+	maxBrandAssetDataURLBytes = 1024 * 1024
+)
+
 func New(repo *repo.Repository, jwtSecret string) *Handler {
 	h := &Handler{
 		repo:                   repo,
@@ -747,7 +753,14 @@ func (h *Handler) updateConfigs(w http.ResponseWriter, r *http.Request) {
 		if key == "" {
 			continue
 		}
-		if err := h.repo.UpsertConfig(key, v, now); err != nil {
+
+		value, err := normalizeAndValidateConfigValue(key, v)
+		if err != nil {
+			response.WriteJSON(w, response.ErrDefault(err.Error()))
+			return
+		}
+
+		if err := h.repo.UpsertConfig(key, value, now); err != nil {
 			response.WriteJSON(w, response.Err(-2, err.Error()))
 			return
 		}
@@ -767,16 +780,24 @@ func (h *Handler) updateSingleConfig(w http.ResponseWriter, r *http.Request) {
 		response.WriteJSON(w, response.ErrDefault("配置名称不能为空"))
 		return
 	}
-	if strings.TrimSpace(req.Name) == "" {
+	name := strings.TrimSpace(req.Name)
+	if name == "" {
 		response.WriteJSON(w, response.ErrDefault("配置名称不能为空"))
 		return
 	}
-	if strings.TrimSpace(req.Value) == "" {
+
+	value, err := normalizeAndValidateConfigValue(name, req.Value)
+	if err != nil {
+		response.WriteJSON(w, response.ErrDefault(err.Error()))
+		return
+	}
+
+	if value == "" && name != "app_logo" && name != "app_favicon" {
 		response.WriteJSON(w, response.ErrDefault("配置值不能为空"))
 		return
 	}
 
-	if err := h.repo.UpsertConfig(strings.TrimSpace(req.Name), req.Value, time.Now().UnixMilli()); err != nil {
+	if err := h.repo.UpsertConfig(name, value, time.Now().UnixMilli()); err != nil {
 		response.WriteJSON(w, response.Err(-2, err.Error()))
 		return
 	}
@@ -784,6 +805,37 @@ func (h *Handler) updateSingleConfig(w http.ResponseWriter, r *http.Request) {
 	response.WriteJSON(w, response.OKEmpty())
 }
 
+func normalizeAndValidateConfigValue(key, value string) (string, error) {
+	switch strings.TrimSpace(key) {
+	case "app_logo", "app_favicon":
+		normalized := strings.TrimSpace(value)
+		if normalized == "" {
+			return "", nil
+		}
+
+		if !strings.HasPrefix(normalized, pngDataURLPrefix) {
+			return "", fmt.Errorf("品牌图片必须通过上传生成 PNG 数据")
+		}
+
+		if len(normalized) > maxBrandAssetDataURLBytes {
+			return "", fmt.Errorf("品牌图片过大，请上传更小图片")
+		}
+
+		payload := strings.TrimSpace(strings.TrimPrefix(normalized, pngDataURLPrefix))
+		if payload == "" {
+			return "", fmt.Errorf("品牌图片数据不能为空")
+		}
+
+		if _, err := base64.StdEncoding.DecodeString(payload); err != nil {
+			return "", fmt.Errorf("品牌图片数据格式无效")
+		}
+
+		return pngDataURLPrefix + payload, nil
+	default:
+		return value, nil
+	}
+}
+
 func (h *Handler) userPackage(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {
 		response.WriteJSON(w, response.ErrDefault("请求失败"))

go-backend/internal/store/model/model.go

@@ -214,7 +214,7 @@ func (GroupPermissionGrant) TableName() string { return "group_permission_grant"
 type ViteConfig struct {
 	ID    int64  `gorm:"primaryKey;autoIncrement" json:"id"`
 	Name  string `gorm:"type:varchar(200);not null;uniqueIndex" json:"name"`
-	Value string `gorm:"type:varchar(200);not null" json:"value"`
+	Value string `gorm:"type:text;not null" json:"value"`
 	Time  int64  `gorm:"not null" json:"time"`
 }
 

go-backend/internal/store/repo/repository.go

@@ -2482,9 +2482,10 @@ func (r *Repository) GetUserTunnelByID(id int64) (*model.UserTunnel, error) {
 
 // ─── Migration ───────────────────────────────────────────────────────
 
-const currentSchemaVersion = 2
+const currentSchemaVersion = 3
 
 var ensurePostgresIDDefaultsFn = ensurePostgresIDDefaults
+var migrateViteConfigValueColumnTypeFn = migrateViteConfigValueColumnType
 
 func getSchemaVersion(db *gorm.DB) int {
 	var v model.SchemaVersion
@@ -2536,10 +2537,55 @@ func migrateSchema(db *gorm.DB) error {
 		return err
 	}
 
+	if ver < 3 {
+		if err := migrateViteConfigValueColumnTypeFn(db); err != nil {
+			return err
+		}
+	}
+
 	setSchemaVersion(db, currentSchemaVersion)
 	return nil
 }
 
+func migrateViteConfigValueColumnType(db *gorm.DB) error {
+	if db == nil {
+		return errors.New("nil db")
+	}
+
+	if !db.Migrator().HasTable(&model.ViteConfig{}) {
+		return nil
+	}
+
+	if db.Dialector.Name() != "postgres" {
+		return nil
+	}
+
+	type columnRow struct {
+		DataType string `gorm:"column:data_type"`
+	}
+
+	var row columnRow
+	if err := db.Raw(
+		`SELECT data_type FROM information_schema.columns
+		 WHERE table_schema = current_schema()
+		   AND table_name = ?
+		   AND column_name = ?`,
+		"vite_config", "value",
+	).Scan(&row).Error; err != nil {
+		return fmt.Errorf("inspect vite_config.value type: %w", err)
+	}
+
+	if strings.EqualFold(row.DataType, "text") {
+		return nil
+	}
+
+	if err := db.Exec(`ALTER TABLE "vite_config" ALTER COLUMN "value" TYPE TEXT`).Error; err != nil {
+		return fmt.Errorf("alter vite_config.value to text: %w", err)
+	}
+
+	return nil
+}
+
 func ensurePostgresIDDefaults(db *gorm.DB) error {
 	if db.Dialector.Name() != "postgres" {
 		return nil

go-backend/internal/store/repo/repository_migrate_test.go

@@ -83,3 +83,95 @@ func TestMigrateSchemaReturnsPostgresIDRepairError(t *testing.T) {
 		t.Fatalf("expected error %v, got %v", wantErr, err)
 	}
 }
+
+func TestMigrateSchemaRunsViteConfigValueMigrationForLegacySchema(t *testing.T) {
+	db, err := gorm.Open(gsqlite.Open(":memory:"), &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Silent),
+	})
+	if err != nil {
+		t.Fatalf("open sqlite: %v", err)
+	}
+	t.Cleanup(func() {
+		sqlDB, _ := db.DB()
+		if sqlDB != nil {
+			_ = sqlDB.Close()
+		}
+	})
+
+	if err := db.Exec(`CREATE TABLE schema_version (version INTEGER NOT NULL DEFAULT 0)`).Error; err != nil {
+		t.Fatalf("create schema_version: %v", err)
+	}
+	if err := db.Exec(`INSERT INTO schema_version(version) VALUES(?)`, 2).Error; err != nil {
+		t.Fatalf("seed schema_version: %v", err)
+	}
+
+	originalIDRepair := ensurePostgresIDDefaultsFn
+	ensurePostgresIDDefaultsFn = func(db *gorm.DB) error {
+		return nil
+	}
+	t.Cleanup(func() {
+		ensurePostgresIDDefaultsFn = originalIDRepair
+	})
+
+	called := 0
+	originalMigrate := migrateViteConfigValueColumnTypeFn
+	migrateViteConfigValueColumnTypeFn = func(db *gorm.DB) error {
+		called++
+		return nil
+	}
+	t.Cleanup(func() {
+		migrateViteConfigValueColumnTypeFn = originalMigrate
+	})
+
+	if err := migrateSchema(db); err != nil {
+		t.Fatalf("migrateSchema: %v", err)
+	}
+
+	if called != 1 {
+		t.Fatalf("expected vite_config migration to run once, got %d", called)
+	}
+}
+
+func TestMigrateSchemaReturnsViteConfigMigrationError(t *testing.T) {
+	db, err := gorm.Open(gsqlite.Open(":memory:"), &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Silent),
+	})
+	if err != nil {
+		t.Fatalf("open sqlite: %v", err)
+	}
+	t.Cleanup(func() {
+		sqlDB, _ := db.DB()
+		if sqlDB != nil {
+			_ = sqlDB.Close()
+		}
+	})
+
+	if err := db.Exec(`CREATE TABLE schema_version (version INTEGER NOT NULL DEFAULT 0)`).Error; err != nil {
+		t.Fatalf("create schema_version: %v", err)
+	}
+	if err := db.Exec(`INSERT INTO schema_version(version) VALUES(?)`, 2).Error; err != nil {
+		t.Fatalf("seed schema_version: %v", err)
+	}
+
+	originalIDRepair := ensurePostgresIDDefaultsFn
+	ensurePostgresIDDefaultsFn = func(db *gorm.DB) error {
+		return nil
+	}
+	t.Cleanup(func() {
+		ensurePostgresIDDefaultsFn = originalIDRepair
+	})
+
+	wantErr := errors.New("vite config migration failed")
+	originalMigrate := migrateViteConfigValueColumnTypeFn
+	migrateViteConfigValueColumnTypeFn = func(db *gorm.DB) error {
+		return wantErr
+	}
+	t.Cleanup(func() {
+		migrateViteConfigValueColumnTypeFn = originalMigrate
+	})
+
+	err = migrateSchema(db)
+	if !errors.Is(err, wantErr) {
+		t.Fatalf("expected error %v, got %v", wantErr, err)
+	}
+}