Fix profile display backfill startup

server/db/mysql/user_identity_test.go

@@ -64,10 +64,14 @@ func TestProfilePublicFromFields(t *testing.T) {
 
 func TestProfileSeedFromPublic(t *testing.T) {
 	nickname, avatar := profileSeedFromPublic(map[string]any{
-		"fn":    "旧昵称",
-		"photo": "file_avatar_1",
+		"fn":             "旧昵称",
+		"avatar_file_id": "file_avatar_1",
 	})
 	if nickname != "旧昵称" || avatar != "file_avatar_1" {
 		t.Fatalf("unexpected profile seed nickname=%q avatar=%q", nickname, avatar)
 	}
+	_, avatar = profileSeedFromPublic(map[string]any{"photo": "https://example.com/avatar.png"})
+	if avatar != "" {
+		t.Fatalf("photo URL must not be treated as avatar_file_id: %q", avatar)
+	}
 }