agent web UI: wrap the OAuth login URL instead of letting it overflow the card

claude's real OAuth URL is one long unbroken query-string token, no
whitespace for the browser to break on. Without overflow-wrap the
<a> just kept going past the login card's right edge instead of
wrapping at the card's bounded width (mara reported this with a
screenshot). overflow-wrap: anywhere lets it break mid-token as a
last resort, scoped to just the URL line (.login-url) rather than
the whole card.

frontend/packages/agent/src/components/LoginFlow.tsx

@@ -93,7 +93,7 @@ function LoginInProgress({ session, onDone }: { session: SessionView | null; onD
       <p class="status-needs-login">◌ L0G1N 1N PR0GRESS</p>
       {session?.url ? (
         <>
-          <p>
+          <p class="login-url">
             ▶{' '}
             <a href={session.url} target="_blank" rel="noreferrer">
               {session.url}