fix: standardize button order, add confirmation dialogs for destructive actions

- Fix Cancel|Save order and add primary/loading props (AppConfigDetailPage)
- Add AlertDialog before stopping deployments (AppsTab)
- Add ConfirmDialog before deleting taps (TapConfigModal)
- Add AlertDialog before killing queries with toast feedback (DatabaseAdminPage)
- Add AlertDialog before removing roles from users (UsersTab)
- Standardize Cancel button to variant="ghost" (TapConfigModal, RouteDetail)
- Add loading prop to ConfirmDialogs (OidcConfigPage, RouteDetail)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/Admin/AppConfigDetailPage.tsx

@@ -309,10 +309,8 @@ export default function AppConfigDetailPage() {
         <Button variant="ghost" size="sm" onClick={() => navigate('/admin/appconfig')}><ArrowLeft size={14} /> Back</Button>
         {editing ? (
           <div className={styles.toolbarActions}>
-            <Button onClick={handleSave} disabled={updateConfig.isPending}>
-              {updateConfig.isPending ? 'Saving\u2026' : 'Save'}
-            </Button>
-            <Button variant="secondary" size="sm" onClick={cancelEditing}>Cancel</Button>
+            <Button variant="ghost" size="sm" onClick={cancelEditing}>Cancel</Button>
+            <Button variant="primary" size="sm" onClick={handleSave} loading={updateConfig.isPending}>Save</Button>
           </div>
         ) : (
           <Button variant="secondary" size="sm" onClick={startEditing}><Pencil size={14} /> Edit</Button>