chore(sync): 上游同步 - 合并 upstream/main 至 37b44444，按新 module 路径收敛冲突

backend/cmd/migrate-schema/fork_env.go

@@ -0,0 +1,8 @@
+// 本项目附加文件（fork 专属）：不改上游 main.go，仅让该命令启动时读取仓库根 .env。
+package main
+
+import "yingce/backend/internal/config"
+
+func init() {
+	config.LoadDotEnv()
+}

backend/cmd/migrate-schema/main.go

@@ -7,13 +7,11 @@ import (
 	"os"
 	"strings"
 
-	"infinite-canvas/backend/internal/canvas"
-	"infinite-canvas/backend/internal/config"
-	"infinite-canvas/backend/internal/database"
+	"yingce/backend/internal/canvas"
+	"yingce/backend/internal/database"
 )
 
 func main() {
-	config.LoadDotEnv()
 	command := "up"
 	if len(os.Args) > 1 {
 		command = strings.ToLower(strings.TrimSpace(os.Args[1]))