fix(ui): register the service worker in production only

SvelteKit's automatic SW registration also runs under `vite dev`, where
the worker intercepted/cached the dev-server e2e suite (42 failures).
Disable auto-registration (kit.serviceWorker.register: false) and
register the worker manually from the root layout guarded by `!dev`, so
`vite dev` and the e2e suite run worker-free while the production build —
and the PWA preview test — still install it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

ui/frontend/svelte.config.js

@@ -11,5 +11,11 @@ export default {
 			fallback: "index.html",
 			strict: true,
 		}),
+		serviceWorker: {
+			// Registered manually in the root layout for production only.
+			// SvelteKit's auto-registration also runs under `vite dev`, where
+			// the worker would intercept and cache the dev-server e2e suite.
+			register: false,
+		},
 	},
 };