Share one user form, add user photos and Revoke, confirm every form

- Settings > Users uses the people UserForm (useFormInit) instead of its
  own copy; it saves in one request through users/save-user, which now
  takes an optional profile photo (setUserProfileImage)
- Revoke action on user rows adds the revoked type, as the edit form would
- Every admin form asks for confirmation before it saves

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/pages/admin/settings/models/(partials)/harness-settings-form.tsx

@@ -56,6 +56,7 @@ export default function HarnessSettingsForm({
 
     const submit = async () => {
         if (!dirty || loading) return;
+        if (!window.confirm(`Save these model settings?`)) return;
 
         setLoading(true);
         setStatus({});

src/pages/admin/settings/models/(partials)/provider-form.tsx

@@ -44,6 +44,7 @@ export default function ProviderForm({ provider, onSaved, onCancel }: Props) {
 
     const submit = async () => {
         if (loading) return;
+        if (!window.confirm(provider?.id ? `Save ${provider.name || "this provider"}?` : `Add ${name || "this provider"}?`)) return;
 
         setLoading(true);
         setError(undefined);