feat(login): three real EA2-seeded personas as quick-switch chips

Seeded HR/CEO/IT directors as real superuser rows in auth_service.user via
auth-service POST /api/v1/auth/register + a one-shot SQL promotion to
is_superuser=TRUE so dev-login resolves them:

  ceo-head@flow-master.ai  → Mariana Cole (Chief Executive)
  hr-head@flow-master.ai   → Aisha Khan   (HR Director)
  it-head@flow-master.ai   → Rohan Patel  (IT Director)

Login page exposes them as three QUICK PERSONA chips that prefill the
operator-id field; clicking SIGN IN AS DEVELOPER then issues a real JWT
for that persona. No mock users.

src/scenes/Login.tsx

@@ -137,6 +137,30 @@ export default function Login() {
             </button>
           )}
         </div>
+
+        {devLoginEnabled && (
+          <div className="login-personas">
+            <div className="login-persona-label">QUICK PERSONA</div>
+            <div className="login-persona-row">
+              {[
+                { key: "ceo", email: "ceo-head@flow-master.ai", title: "Mariana Cole · CEO" },
+                { key: "hr", email: "hr-head@flow-master.ai", title: "Aisha Khan · HR" },
+                { key: "it", email: "it-head@flow-master.ai", title: "Rohan Patel · IT" },
+              ].map((p) => (
+                <button
+                  key={p.key}
+                  type="button"
+                  className="persona-chip"
+                  onClick={() => setEmail(p.email)}
+                  disabled={loading}
+                  title={p.email}
+                >
+                  {p.title}
+                </button>
+              ))}
+            </div>
+          </div>
+        )}
       </div>
     </div>
   );