fix: make API client base URL configurable for green-blue deployments

Previously, all browser clients (AdminDashboardClient, InquiryBrowserClient, etc.)
had hardcoded BaseAddress of http://localhost:5001/taxbaik/api/. This caused
issues when implementing green-blue deployments where ports alternate between
5001/5002.

Changes:
- Add ApiClient:BaseUrl configuration in appsettings.json (default: 5001)
- Update Program.cs to read configuration instead of hardcoding
- All 6 browser clients now use dynamic configuration
- Deployment script prepared for green-blue support (port can be injected via
  ApiClient__BaseUrl environment variable)

Deployment Note:
- For green-blue: Set ApiClient__BaseUrl environment variable before starting
  the service on the alternate port (5002)
- Nginx still routes /taxbaik to the active instance
- Supports zero-downtime deployments

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

TaxBaik.Web/appsettings.json

@@ -14,6 +14,9 @@
   "App": {
     "PublicBaseUrl": "http://178.104.200.7/taxbaik"
   },
+  "ApiClient": {
+    "BaseUrl": "http://localhost:5001/taxbaik/api/"
+  },
   "Telegram": {
     "BotToken": "",
     "ChatId": ""