fix: apply the review items for #718 at merge

- docs/api-reference.md:1222: the tunnel status shape is { running, url, loginConfigured } (getStatus() returns only running and url)
- src/web/routes/system-routes.ts:1233: the unauthenticated-tunnel warning keys on !isLoginConfigured(), so it no longer fires in multi-user mode
- test/install-sh-invariants.test.ts:537: install.sh must not contain --allow-unauthenticated-tunnel either (it writes service argv as well as env)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/install-sh-invariants.test.ts

@@ -534,4 +534,5 @@ describe('install.sh review fixes for #460', () => {
 
 it('install.sh never contains the unauthenticated tunnel opt-in', () => {
   expect(SOURCE).not.toContain('CODEMAN_ALLOW_UNAUTHENTICATED_TUNNEL');
+  expect(SOURCE).not.toContain('--allow-unauthenticated-tunnel');
 });