feat: connect resource library workflows

docs/superpowers/specs/2026-03-28-resource-library-design.md

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+# Resource Library Design
+
+**Goal:** Build a real resource-library backend for models, scenes, and garments with S3 direct-upload preparation, persisted resource metadata, and list APIs that the existing frontend library pages can consume.
+
+**Scope:** Replace mock resource-library data with a dedicated backend resource domain. The first slice supports public-read assets, presigned upload preparation, one-shot resource creation, and real list retrieval. Upload UI is out of scope; API tests and existing frontend readers are the verification path.
+
+**Decisions**
+
+- Resource-library records are independent from order-generated assets.
+- Files are stored in S3 and read publicly through the configured CDN hostname.
+- Uploads use a two-step direct-upload flow:
+  1. Backend issues presigned upload parameters and storage metadata.
+  2. Client uploads to S3 and then creates the resource record with uploaded file metadata.
+- A resource can include:
+  - one original file
+  - one thumbnail file
+  - multiple gallery files
+- Type-specific fields in the first version:
+  - model: `gender`, `age_group`
+  - scene: `environment`
+  - garment: `category`
+- Garment category remains a plain string for now. Config management can come later.
+
+**Backend Shape**
+
+- Add a dedicated `library_resources` table for business metadata.
+- Add a dedicated `library_resource_files` table for uploaded file references.
+- Add enums for resource type, file role, and optional status/environment metadata.
+- Add API routes for:
+  - upload presign
+  - resource create
+  - resource list
+- Keep the existing order asset model untouched.
+
+**Frontend Shape**
+
+- Keep the existing frontend library pages and submit-workbench readers.
+- Replace the current mock BFF implementation with a proxy that calls the new backend list endpoint and maps backend payloads into the existing `LibraryItemVM`.
+- Upload UI is deferred. No new client-side upload forms are required in this slice.
+
+**Verification**
+
+- Backend integration tests cover:
+  - presign response generation
+  - resource creation with original/thumbnail/gallery files
+  - filtered resource listing by type and type-specific fields
+- Frontend route tests cover:
+  - successful proxying and mapping from backend payload to existing view-model shape
+  - unsupported library-type rejection remains normalized