feat: add centralized error logging system

- Implemented Error Log API to capture and store error logs from various services.
- Updated admin_ui to include Error Log Viewer component for inspecting logs.
- Enhanced error handling in auth_api, employee_api, and transit_api to report errors to the Error Log API.
- Modified existing services to utilize the new error logging functionality.
- Updated Docker Compose configuration to include the Error Log API service.
- Added error logging service in bus_terminal for Flutter application.

bus_terminal/lib/services/error_log_service.dart

@@ -0,0 +1,26 @@
+import 'dart:convert';
+import 'package:http/http.dart' as http;
+
+class ErrorLogService {
+  static const String _apiBaseUrl = 'https://transit.xtransit.testinstance.nl';
+
+  static Future<void> report({
+    required String service,
+    required String partOfService,
+    required String error,
+  }) async {
+    try {
+      await http.post(
+        Uri.parse('$_apiBaseUrl/error_log'),
+        headers: {'Content-Type': 'application/json'},
+        body: jsonEncode({
+          'service': service,
+          'partOfService': partOfService,
+          'error': error,
+        }),
+      );
+    } catch (_) {
+      // Intentionally ignore logging failures.
+    }
+  }
+}