feat: handle remove file source

src/lib/config.ts

@@ -102,6 +102,15 @@ async function initConfig() {
               });
             }
           });
+
+          // 检查现有源是否在 fileConfig.api_site 中，如果不在则标记为 custom
+          const apiSiteKeys = new Set(apiSiteEntries.map(([key]) => key));
+          adminConfig.SourceConfig.forEach((source) => {
+            if (!apiSiteKeys.has(source.key)) {
+              source.from = 'custom';
+            }
+          });
+
           const existedUsers = new Set(
             (adminConfig.UserConfig.Users || []).map((u) => u.username)
           );