feat(inbounds): add multi-select and bulk delete

Mirror the clients page: checkbox selection on the desktop table and on
mobile cards, with a danger Delete button in the toolbar that removes all
selected inbounds in one call.

Backend adds POST /panel/api/inbounds/bulkDel, which loops the existing
DelInbound per id (xray restarts at most once) and returns {deleted,
skipped}. Frontend shows a confirm modal plus a result toast, clears the
selection on success, adds bulk-delete i18n keys across all 13 languages,
and documents the endpoint in the in-panel API docs.

frontend/src/pages/api-docs/endpoints.ts

@@ -149,6 +149,13 @@ export const sections: readonly Section[] = [
           { name: 'id', in: 'path', type: 'number', desc: 'Inbound ID.' },
         ],
       },
+      {
+        method: 'POST',
+        path: '/panel/api/inbounds/bulkDel',
+        summary: 'Delete many inbounds in one call. Processes the list sequentially; failures are reported per id and the rest still proceed. Restarts xray at most once.',
+        body: '{\n  "ids": [1, 2, 3]\n}',
+        response: '{\n  "success": true,\n  "obj": {\n    "deleted": 2,\n    "skipped": [\n      { "id": 3, "reason": "..." }\n    ]\n  }\n}',
+      },
       {
         method: 'POST',
         path: '/panel/api/inbounds/update/:id',