test(auth): add isPublicRoute boundary tests for sub-paths and trailing slash

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

frontend/src/hooks.server.test.ts

@@ -39,6 +39,15 @@ describe('auth guard (hooks.server.ts handle)', () => {
 		expect(resolve).toHaveBeenCalledWith(event);
 	});
 
+	it.each(['/login', '/login/', '/register', '/invite/abc123'])(
+		'allows public route %s without auth',
+		async (path) => {
+			const { event, resolve } = createEvent(path);
+			await handle({ event, resolve });
+			expect(resolve).toHaveBeenCalledWith(event);
+		}
+	);
+
 	it.each(['/_app/immutable/chunks/app.js', '/favicon.ico'])(
 		'allows static asset %s without auth',
 		async (path) => {