feat(metadata-admin): db-only items show Delete action instead of Reset

For two-tier metadata types (allowRuntimeCreate true, allowOrgOverride
false — e.g. hook, trigger, validation), the prior UX showed 'Reset
overlay' on DB-only items, which is misleading because there is no
underlying artifact to reset to. The action actually deletes the row.

- ResourceEditPage: doReset() branches on itemIsArtifact; DB-only path
  navigates back to the list after successful delete
- Button label/icon swap to Trash2/Delete when item is DB-only
- i18n: add engine.edit.delete + engine.edit.deleteConfirm in EN+ZH

Browser-verified end-to-end on hook type:
- artifact-locked item: shows lock banner + '新建' CTA (no delete button)
- DB-only item: shows '删除' button, confirmation dialog uses new key,
  delete navigates back to directory page

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: os-zhuang

packages/app-shell/src/views/metadata-admin/ResourceEditPage.tsx

@@ -25,6 +25,7 @@ import { useNavigate, useParams } from 'react-router-dom';
 import {
   Save,
   RotateCcw,
+  Trash2,
   History,
   Link2,
   Loader2,
@@ -386,19 +387,33 @@ export function MetadataResourceEditPage({
   }
 
   async function doReset() {
-    if (!confirm(`Reset overlay for ${type}/${name}? Code-level value will be restored.`)) {
+    // Two semantics:
+    //   - artifact-backed item: "Reset overlay" — keep the code default.
+    //   - DB-only item: "Delete" — the item disappears entirely (no
+    //     artifact baseline to fall back to). Navigate back to the list
+    //     since the current URL no longer refers to anything.
+    const itemIsArtifact = !createMode && layered?.code != null;
+    const confirmKey = itemIsArtifact
+      ? 'engine.edit.resetConfirm'
+      : 'engine.edit.deleteConfirm';
+    if (!confirm(tFormat(confirmKey, locale, { type, name: name ?? '' }))) {
       return;
     }
     setSaving(true);
     setError(null);
     try {
       await client.reset(type, name);
-      const lay = await client.layered<any>(type, name);
-      setLayered(lay);
-      const fresh = (lay.effective ?? lay.code ?? {}) as Record<string, unknown>;
-      setDraft(fresh);
-      draftSnapshotRef.current = fresh;
-      setEditing(false);
+      if (itemIsArtifact) {
+        const lay = await client.layered<any>(type, name);
+        setLayered(lay);
+        const fresh = (lay.effective ?? lay.code ?? {}) as Record<string, unknown>;
+        setDraft(fresh);
+        draftSnapshotRef.current = fresh;
+        setEditing(false);
+      } else {
+        // No artifact baseline → return to the list view.
+        navigate(`../`);
+      }
     } catch (err: any) {
       setError(err?.message ?? String(err));
     } finally {
@@ -512,8 +527,17 @@ export function MetadataResourceEditPage({
           )}
           {!createMode && canWrite && layered?.overlay && (
             <Button variant="ghost" size="sm" onClick={doReset} disabled={saving}>
-              <RotateCcw className="h-4 w-4 mr-1" />
-              {t('engine.edit.reset', locale)}
+              {isArtifactItem ? (
+                <>
+                  <RotateCcw className="h-4 w-4 mr-1" />
+                  {t('engine.edit.reset', locale)}
+                </>
+              ) : (
+                <>
+                  <Trash2 className="h-4 w-4 mr-1" />
+                  {t('engine.edit.delete', locale)}
+                </>
+              )}
             </Button>
           )}
           {!createMode && (

packages/app-shell/src/views/metadata-admin/i18n.ts

@@ -152,6 +152,8 @@ const ENGINE_STRINGS_EN: Record<string, string> = {
   'engine.edit.save': 'Save',
   'engine.edit.reset': 'Reset overlay',
   'engine.edit.resetConfirm': 'Reset overlay for {type}/{name}?',
+  'engine.edit.delete': 'Delete',
+  'engine.edit.deleteConfirm': 'Delete {type}/{name}? This cannot be undone.',
   'engine.edit.history': 'History',
   'engine.edit.layers': 'Layers',
   'engine.edit.references': 'References',
@@ -269,6 +271,8 @@ const ENGINE_STRINGS_ZH: Record<string, string> = {
   'engine.edit.save': '保存',
   'engine.edit.reset': '重置覆盖',
   'engine.edit.resetConfirm': '重置 {type}/{name} 的覆盖层？',
+  'engine.edit.delete': '删除',
+  'engine.edit.deleteConfirm': '删除 {type}/{name}？此操作不可撤销。',
   'engine.edit.history': '历史',
   'engine.edit.layers': '层次',
   'engine.edit.references': '引用关系',