fix: add TraceLayer and Vite proxy config (supporting changes)

- Add tower-http TraceLayer to Axum router for request logging
- Configure Vite dev server proxy for /api and /media to localhost:3000
- Add TEST_GUIDE.md for manual frontend testing steps

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

frontend/vite.config.ts

@@ -3,5 +3,11 @@ import tailwindcss from '@tailwindcss/vite';
 import { defineConfig } from 'vite';
 
 export default defineConfig({
-	plugins: [tailwindcss(), sveltekit()]
+	plugins: [tailwindcss(), sveltekit()],
+	server: {
+		proxy: {
+			'/api': 'http://localhost:3000',
+			'/media': 'http://localhost:3000'
+		}
+	}
 });