feat: per-position camera settings, material alias dialog, product delete, media browser links

- Per-render-position focal_length_mm/sensor_width_mm (DB → pipeline → Blender)
- FOV-based camera distance with min clamp fix for wide-angle lenses
- Unmapped materials blocking dialog on "Dispatch Renders" with batch alias creation
- Material check endpoint (GET /orders/{id}/check-materials)
- Batch alias endpoint (POST /materials/batch-aliases)
- Quick-map "No alias" badges on Materials page
- Full product hard-delete with storage cleanup (MinIO + disk files + orphaned CadFile)
- Delete button on ProductDetail page with confirmation
- Clickable product names in Media Browser (links to product page)
- Single-line render dispatch/retry (POST /orders/{id}/lines/{id}/dispatch-render)

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

frontend/src/pages/Admin.tsx

@@ -243,6 +243,12 @@ export default function AdminPage() {
     onError: (e: any) => toast.error(e.response?.data?.detail || 'Failed'),
   })
 
+  const purgeRenderMediaMut = useMutation({
+    mutationFn: () => api.delete('/admin/settings/purge-render-media'),
+    onSuccess: (res) => toast.success(res.data.message || 'Render media purged'),
+    onError: (e: any) => toast.error(e.response?.data?.detail || 'Failed'),
+  })
+
   const [smtpDraft, setSmtpDraft] = useState<Partial<Settings>>({})
   const smtp = { ...settings, ...smtpDraft } as Settings
 
@@ -1017,6 +1023,23 @@ export default function AdminPage() {
                 </button>
                 <p className="text-xs text-content-muted">Removes STEP files, thumbnails, and DB records not linked to any product.</p>
               </div>
+              <div className="flex flex-col gap-1">
+                <button
+                  onClick={() => setConfirmState({
+                    open: true,
+                    title: 'Purge All Rendered Media',
+                    message: 'Delete ALL still renders and turntable animations? Thumbnails, GLBs, and USD masters are kept. This cannot be undone.',
+                    onConfirm: () => { purgeRenderMediaMut.mutate(); setConfirmState(s => ({ ...s, open: false })) },
+                  })}
+                  disabled={purgeRenderMediaMut.isPending}
+                  className="btn-secondary text-sm w-full justify-start text-red-500"
+                  title="Delete all still and turntable render media (files + DB records)"
+                >
+                  <Trash2 size={14} className={purgeRenderMediaMut.isPending ? 'animate-spin' : ''} />
+                  {purgeRenderMediaMut.isPending ? 'Purging…' : 'Purge All Stills & Turntables'}
+                </button>
+                <p className="text-xs text-content-muted">Deletes all rendered images and animations. Thumbnails, GLBs, and USD files are preserved.</p>
+              </div>
               <div className="flex flex-col gap-1">
                 <button
                   onClick={() => reextractMetadataMut.mutate()}