release(secrets-mcp): 0.5.8 — 修复更换密码短语流程

- secrets-core: change_user_key() 事务内全量解密并重加密 secrets
- web: POST /api/key-change；已有密钥时拒绝 POST /api/key-setup（409）
- dashboard: 更换密码需当前密码，调用 key-change
- 同步 Cargo.lock

Cargo.lock

@@ -2066,7 +2066,7 @@ dependencies = [
 
 [[package]]
 name = "secrets-mcp"
-version = "0.5.7"
+version = "0.5.8"
 dependencies = [
  "anyhow",
  "askama",