Build 2602261605: invite trace and cross-system user lifecycle

frontend/app/signup/page.tsx

@@ -135,7 +135,7 @@ function SignupPageContent() {
     <main className="card auth-card">
       <BrandingLogo className="brand-logo brand-logo--login" />
       <h1>Create account</h1>
-      <p className="lede">Use an invite code from your admin to create a Magent account.</p>
+      <p className="lede">Use an invite code from your admin to create your Jellyfin-backed Magent account.</p>
       <form onSubmit={submit} className="auth-form">
         <label>
           Invite code
@@ -203,7 +203,7 @@ function SignupPageContent() {
         {status && <div className="status-banner">{status}</div>}
         <div className="auth-actions">
           <button type="submit" disabled={!canSubmit}>
-            {loading ? 'Creating account…' : 'Create account'}
+            {loading ? 'Creating account…' : 'Create account (Jellyfin + Magent)'}
           </button>
         </div>
         <button type="button" className="ghost-button" disabled={loading} onClick={() => router.push('/login')}>