feat: refine FluentUrl class and enhance URL serializer with improved parsing logic

lib/core/fluent-url.ts

@@ -13,7 +13,7 @@ import type {
 } from '@/shared/types'
 
 export class FluentUrl {
-  private config: FluentUrlConfig
+  private readonly config: FluentUrlConfig
   private readonly protocol?: string
   private readonly hostname?: string
   private readonly paths: string[]
@@ -76,7 +76,7 @@ export class FluentUrl {
 
   public clone(
     options?: Partial<FLuentUrlPlainObject>,
-    config?: FluentUrlConfig,
+    config?: Partial<FluentUrlConfig>,
   ): FluentUrl {
     return new FluentUrl(
       mergeOptions(