feat: 重构环境配置，移除 openim_common 依赖并优化主页 URL 获取逻辑

openim_common/lib/src/config.dart

@@ -1,17 +1,9 @@
-enum Environment {
-  production,
-}
-
 class Config {
-  static const Environment currentEnvironment = Environment.production;
-
-  static final Map<Environment, List<String>> _environmentHosts = {
-    Environment.production: [
-      'h5-im.imharry.work',
-    ],
-  };
+  static const List<String> defaultEnvironmentHosts = [
+    'h5-im.imharry.work',
+  ];
 
   static List<String> get environmentHosts {
-    return _environmentHosts[currentEnvironment] ?? const [];
+    return defaultEnvironmentHosts;
   }
 }