docs: add generated asset prefix baseline

docs/technical/SPACETIMEDB_AXUM_OSS_BACKEND_REWRITE_DESIGN_2026-04-20.md

@@ -133,9 +133,10 @@ SpacetimeDB Module
 Aliyun OSS
 ├─ generated-character-drafts
 ├─ generated-characters
+├─ generated-animations
 ├─ generated-custom-world-scenes
+├─ generated-custom-world-covers
 ├─ generated-qwen-sprites
-├─ generated-cover-images
 └─ editor-exports / temp-uploads / workflow-cache
 ```
 
@@ -468,10 +469,10 @@ Axum 第一阶段需要兼容当前项目的这些约定：
 ```text
 generated-character-drafts/{character_id}/{job_id}/{file}
 generated-characters/{character_id}/visual/{asset_id}/{file}
-generated-characters/{character_id}/animation/{asset_id}/{action}/{file}
+generated-animations/{character_id}/{animation_set_id}/{action}/{file}
 generated-custom-world-scenes/{profile_id}/{landmark_id}/{asset_id}/{file}
 generated-qwen-sprites/{role_id}/{sheet_id}/{file}
-generated-cover-images/{profile_id}/{asset_id}/{file}
+generated-custom-world-covers/{profile_id}/{asset_id}/{file}
 editor-cache/{resource_type}/{resource_id}/{file}
 workflow-cache/{workflow_type}/{workflow_id}.json
 ```
@@ -522,8 +523,10 @@ workflow-cache/{workflow_type}/{workflow_id}.json
 
 1. `/generated-character-drafts/*`
 2. `/generated-characters/*`
-3. `/generated-custom-world-scenes/*`
-4. `/generated-qwen-sprites/*`
+3. `/generated-animations/*`
+4. `/generated-custom-world-scenes/*`
+5. `/generated-custom-world-covers/*`
+6. `/generated-qwen-sprites/*`
 
 ## 12. 关键业务流设计