feat: bulk approve/hide pending devices (#70)

- Backend: POST /scan/pending/bulk-approve and /scan/pending/bulk-hide endpoints (registered before dynamic routes to avoid conflict); bulk-approve response includes device_ids for frontend mapping
- Frontend: PendingDevicesPanel gains per-row checkboxes, select-all, and a bulk action bar (Approve N / Hide N) that appears when ≥1 device is selected
- Tests: 6 new backend API tests + 7 new frontend UI tests for bulk selection flows

frontend/src/api/client.ts

@@ -60,6 +60,8 @@ export const scanApi = {
   approve: (id: string, nodeData: object) => api.post(`/scan/pending/${id}/approve`, nodeData),
   hide: (id: string) => api.post(`/scan/pending/${id}/hide`),
   ignore: (id: string) => api.post(`/scan/pending/${id}/ignore`),
+  bulkApprove: (ids: string[]) => api.post<{ approved: number; node_ids: string[]; device_ids: string[]; skipped: number }>('/scan/pending/bulk-approve', { device_ids: ids }),
+  bulkHide: (ids: string[]) => api.post<{ hidden: number; skipped: number }>('/scan/pending/bulk-hide', { device_ids: ids }),
   stop: (runId: string) => api.post(`/scan/${runId}/stop`),
   getConfig: () => api.get<{ ranges: string[] }>('/scan/config'),
   saveConfig: (data: { ranges: string[] }) => api.post('/scan/config', data),