refactor: auto-prompt for notification permission, drop OT alerts button

Browsers already gate Notification.requestPermission behind a native
prompt, so a dedicated button was redundant UI clutter. Prompting on
load (only when permission state is "default") keeps the flow and
clears space in the banner for future notification types.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/templates/index.html

@@ -46,9 +46,6 @@
         </div>
         <div class="banner-actions">
             <a class="banner-bracket-link" href="/bracket">Bracket</a>
-            <button class="banner-notify" type="button" title="Notify me on playoff OT" aria-label="Enable OT notifications">
-                <span class="bell-label">OT alerts</span>
-            </button>
         </div>
     </section>
     <main>