feat: Add alert processing functionality and UI feedback

templates/base.html

@@ -16,6 +16,9 @@
         <form action="/sync_emails" method="post" style="display:inline-block; margin-left:12px;">
           <button type="submit">Process Emails</button>
         </form>
+        <form action="/process" method="post" style="display:inline-block; margin-left:12px;">
+          <button type="submit">Process Alerts</button>
+        </form>
       </nav>
     </div>
   </header>

templates/threads.html

@@ -4,6 +4,11 @@
     <div class="col">
       <h2>Threads{% if account %} for {{ account }}{% endif %}</h2>
       <p class="muted">Latest updated threads. Click an ID to view details and AI analysis.</p>
+      {% if alerts_processed is not none %}
+        <div class="alert success" style="margin-bottom:12px;">
+          ✓ Alerts processed! {{ alerts_processed }} thread(s) were checked for alerts.
+        </div>
+      {% endif %}
       {% if status %}
         <div class="muted" style="margin-top:6px;">
           {% if status.sync_in_progress %}