fix: upload body limit, role case, and connection drain (v0.12.1)

- Disable Axum's 2 MB default body limit on the upload route so large
  photos/videos are accepted without HTTP 400
- Serialize UserRole as lowercase in JWT so the frontend role checks
  ('guest'/'host'/'admin') match correctly
- Drain multipart body before returning early upload errors (rate-limit,
  ban, event-lock) to keep the HTTP keep-alive connection clean and
  prevent cascading Netzwerkfehler / empty-500 responses
- Add TraceLayer for request logging and Vite dev proxy config

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'
+		}
+	}
 });