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/ansible.html

@@ -39,7 +39,7 @@
       <span style="color:var(--text-muted);font-size:0.78rem;">Click to select — add to a host's <code>authorized_keys</code> to authorize Steward manually.</span>
     </div>
     <form method="post" action="/settings/ansible/generate-key"
-          onsubmit="return confirm('Regenerate the managed key? Already-provisioned hosts will reject Steward until you re-provision them.');">{{ csrf_field() }}
+          data-confirm="Regenerate the managed key? Already-provisioned hosts will reject Steward until you re-provision them.">{{ csrf_field() }}
       <button type="submit" class="btn btn-ghost btn-sm">Regenerate key</button>
     </form>
     {% else %}