fix(wire): resolveDataDir 改用 cfg.DataDir（.env 的 DATA_DIR 真正生效，不再落平台默认目录）

cmd/cyrene/wire.go

@@ -480,10 +480,11 @@ func (a *app) close(ctx context.Context) {
 	a.log.Info("cyrene shutdown complete")
 }
 
-// resolveDataDir returns the configured data directory, or the OS-appropriate
-// default when DATA_DIR is not exported to the process environment.
+// resolveDataDir returns the configured data directory (from .env / env, via
+// cfg.DataDir), falling back to the OS-appropriate default only when no
+// directory is configured.
 func resolveDataDir(cfg *config.Config) string {
-	if _, ok := os.LookupEnv("DATA_DIR"); ok {
+	if cfg.DataDir != "" {
 		return cfg.DataDir
 	}
 	return platform.DefaultDataDir()