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/_plugin_repos.html

@@ -18,7 +18,7 @@
         </div>
         <div style="display:flex;gap:0.4rem;flex-shrink:0;">
           <button class="btn btn-ghost btn-sm" style="font-size:0.78rem;"
-                  onclick="toggleRepoEdit({{ idx }})">Edit</button>
+                  onclick="toggleRepoEdit({{ idx|int }})">Edit</button>
           <button class="btn btn-danger btn-sm" style="font-size:0.78rem;"
                   hx-post="/settings/plugins/repos/{{ idx }}/remove"
                   hx-target="#plugin-repos"
@@ -47,7 +47,7 @@
           <div style="display:flex;gap:0.5rem;margin-top:0.75rem;">
             <button type="submit" class="btn btn-sm">Save</button>
             <button type="button" class="btn btn-ghost btn-sm"
-                    onclick="toggleRepoEdit({{ idx }})">Cancel</button>
+                    onclick="toggleRepoEdit({{ idx|int }})">Cancel</button>
           </div>
         </form>
       </div>