fix(auth): land on home after gate entry; align the @humain e2e to the identifier flow

Removing ConnexionScreen dropped its post-login navigate('/home'). Since the
identifier is now entered at the barrier (before the broker round-trip), on return
the app can load at '/' (WelcomeScreen) with a session already open. AuthGate now
redirects welcome→/home once connected AND identified (gate-disabled paths, i.e.
@e2e/@data harness, are exempt).

Update the @humain assisted-import e2e (the real staging flow, the coverage for
this page) to the new UX: the tester types an identifier then clicks « Entrer »
(one act), and lands directly on home — the 'choisir un nom d'utilisateur'
(ConnexionScreen) steps are removed. Step bindings verified; tsc + build green.
Doctrine: knowledge_multibrowser-harness.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/app/AuthGate.tsx

@@ -13,10 +13,11 @@
  * screens, not the auth flow). Absent → gate ON.
  */
 
-import type { ReactNode } from 'react';
+import { useEffect, type ReactNode } from 'react';
 import { useNextGraph } from '../shared/context/NextGraphContext';
 import { useAccount } from '../shared/context/AccountContext';
 import { AccessGateScreen } from '../modules/auth/screens/AccessGateScreen';
+import { useRouter, useNavigate } from './router';
 
 declare global {
   // eslint-disable-next-line no-var
@@ -27,6 +28,18 @@ const GATE_DISABLED = globalThis.__FESTIPOD_ACCESS_GATE_DISABLED__ === true;
 export function AuthGate({ children }: { children: ReactNode }) {
   const { status, error, connect } = useNextGraph();
   const { username, login } = useAccount();
+  const { route } = useRouter();
+  const navigate = useNavigate();
+
+  // Once connected AND identified, leave the disconnected welcome screen for the
+  // app home. The identifier is now set at the barrier (before the broker
+  // round-trip), so on return the app can land on '/' with a session already
+  // open; the removed ConnexionScreen used to do this navigate on login.
+  useEffect(() => {
+    if (!GATE_DISABLED && status === 'connected' && username && route.page === 'welcome') {
+      navigate('/home');
+    }
+  }, [status, username, route.page, navigate]);
 
   // Gate explicitly disabled (no-gate build / @e2e harness) → straight to app.
   if (GATE_DISABLED) {