Sprint 9: add tenant-driven API resolution layer

src/app/services/location.service.ts

@@ -1,7 +1,7 @@
 import { Injectable, signal, computed } from '@angular/core';
 import { HttpClient } from '@angular/common/http';
 import { Region, GeoIpResponse } from '../models/location.model';
-import { environment } from '../../environments/environment';
+import { ApiConfigService } from '../core/config/api-config.service';
 
 const STORAGE_KEY = 'selected_region';
 
@@ -26,16 +26,17 @@ export class LocationService {
   /** Computed region id for API calls — empty string means global */
   readonly regionId = computed(() => this.regionSignal()?.id ?? '');
 
-  private readonly apiUrl = environment.apiUrl;
-
-  constructor(private http: HttpClient) {
+  constructor(
+    private readonly http: HttpClient,
+    private readonly apiConfig: ApiConfigService
+  ) {
     this.loadRegions();
     this.restoreFromStorage();
   }
 
   /** Fetch available regions from backend */
   loadRegions(): void {
-    this.http.get<Region[]>(`${this.apiUrl}/regions`).subscribe({
+    this.http.get<Region[]>(`${this.apiConfig.getBaseUrl()}/regions`).subscribe({
       next: (regions) => {
         this.regionsSignal.set(regions);
         // If we have a stored region, validate it still exists