feat: serve derivative files via GET /assets/{id}/derivatives/{profile}

- ReadDerivativeHandler queries DerivativeRepository + FileStoragePort
- Profile URL param: thumbnail, thumbnail_large, web_optimized, video_sd
- Immutable cache headers (derivatives don't change once generated)
- Wired into bootstrap catalog service builder

crates/application/src/catalog/queries/mod.rs

@@ -1,3 +1,4 @@
 pub mod get_asset;
 pub mod get_timeline;
 pub mod read_asset_file;
+pub mod read_derivative;