feat: add environment configuration files and update API base URL handling for production

src/lib/api/client.ts

@@ -12,7 +12,15 @@ export class BaseApiClient implements ApiClient {
   }
 
   private buildURL(endpoint: string, params?: Record<string, string | number | boolean | undefined>): string {
-    const url = new URL(endpoint, this.baseURL)
+    let url: URL
+    
+    if (this.baseURL) {
+      // Full base URL provided
+      url = new URL(endpoint, this.baseURL)
+    } else {
+      // Use relative URL (for reverse proxy)
+      url = new URL(endpoint, window.location.origin)
+    }
     
     if (params) {
       Object.entries(params).forEach(([key, value]) => {
@@ -22,7 +30,7 @@ export class BaseApiClient implements ApiClient {
       })
     }
     
-    return url.toString()
+    return this.baseURL ? url.toString() : url.pathname + url.search
   }
 
   private async request<T>(