fix(ui): delete prompts use data-confirm, so a quote in a name no longer runs script (#5099)

#5099 "A name containing a quote runs script when an admin clicks Delete".
Inline handlers like onclick="return confirm('Delete {{ rule.name }}?')" are
HTML-decoded before the JavaScript is parsed, so autoescaping did not stop a
name such as  x');fetch(…);//  from running.

- Every prompt (22 handlers, plus the docker prune and token revoke ones)
  is now data-confirm="…", read through dataset by one submit listener in
  base.html; nothing rendered is parsed as JavaScript.
- The remaining inline handlers take integers only (|int), and the time
  range buttons pass this.dataset.range.
- tests/test_inline_handlers.py fails on any {{ }} in an inline handler that
  is not |int, with a self-test; tests/_templates.py is the one template
  walker the template guards now share.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

steward/templates/settings/plugins.html

@@ -54,7 +54,7 @@
   <div class="section-title">Monitoring capabilities</div>
   <form method="post" action="/settings/plugins/restart/"
         hx-post="/settings/plugins/restart/" hx-target="#restart-banner" hx-swap="outerHTML"
-        onsubmit="return confirm('Restart the app now? This will briefly interrupt all monitoring.')"
+        data-confirm="Restart the app now? This will briefly interrupt all monitoring."
         style="margin:0;">{{ csrf_field() }}
     <button type="submit" class="btn btn-ghost btn-sm" style="font-size:0.78rem;">Restart App</button>
   </form>
@@ -134,7 +134,7 @@
       </div>
       {% if orphan.removable %}
       <form method="post" action="/settings/plugins/orphans/{{ orphan.name }}/remove/"
-            onsubmit="return confirm('Remove stored settings for &quot;{{ orphan.name }}&quot;? Its saved configuration, including any credentials, will be discarded. This cannot be undone.');"
+            data-confirm="Remove stored settings for &quot;{{ orphan.name }}&quot;? Its saved configuration, including any credentials, will be discarded. This cannot be undone."
             style="margin:0;flex-shrink:0;">{{ csrf_field() }}
         <button type="submit" class="btn btn-danger btn-sm" style="font-size:0.78rem;">Remove</button>
       </form>