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>

backend/app/domains/media/router.py

@@ -432,6 +432,24 @@ async def delete_asset_permanent(asset_id: uuid.UUID, db: AsyncSession = Depends
     return {"ok": True}
 
 
+@router.post("/batch-delete")
+async def batch_delete_assets(
+    asset_ids: list[uuid.UUID],
+    _user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Permanently delete multiple MediaAsset records."""
+    from app.utils.auth import require_global_admin
+    require_global_admin(_user)
+
+    deleted = 0
+    for aid in asset_ids:
+        ok = await service.delete_media_asset(db, aid)
+        if ok:
+            deleted += 1
+    return {"deleted": deleted, "requested": len(asset_ids)}
+
+
 @router.post("/cleanup-orphaned")
 async def cleanup_orphaned_assets(
     _user: User = Depends(get_current_user),