fix: use WORKER_URL for networking API to fix connections loading

The connectionService was using a relative path '/api/networking' which
caused requests to go to the Pages frontend URL instead of the Worker API.
This resulted in HTML being returned instead of JSON.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/lib/networking/connectionService.ts

@@ -19,12 +19,13 @@ import type {
   GraphEdge,
   TrustLevel,
 } from './types';
+import { WORKER_URL } from '../../constants/workerUrl';
 
 // =============================================================================
 // Configuration
 // =============================================================================
 
-const API_BASE = '/api/networking';
+const API_BASE = `${WORKER_URL}/api/networking`;
 
 // =============================================================================
 // Helper Functions