feat(E): add MediaAsset catalog — model, CRUD API, MediaBrowser UI

Migration 040: media_assets table with RLS (tenant_isolation + admin_bypass).
domains/media/: MediaAsset model, schemas, service, router with ZIP-download.
publish_asset Celery task in rendering/tasks.py.
core/storage.py: download_bytes() method for MinIO + LocalStorage.
frontend: MediaBrowser.tsx (grid/list, multi-select, zip-download, pagination) + api/media.ts.
Route /media (AdminRoute) + sidebar link with Image icon for admin+pm.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/domains/media/schemas.py

@@ -0,0 +1,26 @@
+import uuid
+from datetime import datetime
+from pydantic import BaseModel
+from app.domains.media.models import MediaAssetType
+
+
+class MediaAssetOut(BaseModel):
+    id: uuid.UUID
+    tenant_id: uuid.UUID | None
+    product_id: uuid.UUID | None
+    cad_file_id: uuid.UUID | None
+    order_line_id: uuid.UUID | None
+    workflow_run_id: uuid.UUID | None
+    asset_type: MediaAssetType
+    storage_key: str
+    file_size_bytes: int | None
+    mime_type: str | None
+    width: int | None
+    height: int | None
+    duration_s: float | None
+    render_config: dict | None
+    is_archived: bool
+    created_at: datetime
+    download_url: str | None = None
+
+    model_config = {"from_attributes": True}