Add project soft-delete with workspace archival

- Add delete button (×) to sidebar project list, shown on hover
- Soft-delete: mark projects as deleted in DB instead of hard delete
- Move workspace files to /app/data/deleted/ folder on deletion
- Filter deleted projects from list query
- Auto-select next project after deleting current one
- Also includes agent prompt improvements for reverse proxy paths

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

doc/todo.md

@@ -2,8 +2,12 @@ context compaction
 
 rag / kb
 
+内置一个向量数据库和kb管理能力吧，kb_search，管理界面简单点，cpu做embedding就够
+
 template
 
+---
+时间观察app
 ---
 
 ## 代码啰嗦/可精简