fix: enhance proxy configuration with password preservation and UI improvements

- Add 'enabled' field to ProxyConfig for preserving config when disabled
- Mask proxy password in API responses (return '***' instead of actual password)
- Preserve existing password on update when new password not provided
- Add URL encoding for proxy credentials (handle special chars like @, :, /)
- Enhanced URL validation: block SOCKS4, require valid host, forbid embedded auth
- UI improvements: use Switch component, dynamic password placeholder
- Add confirmation dialog for orphaned credentials (URL empty but has username/password)
- Prevent browser password autofill with randomized IDs and CSS text-security
- Unify ProxyConfig type definition in types.ts

src/models/endpoint_models.py

@@ -110,8 +110,8 @@ class ProviderEndpointResponse(BaseModel):
     # 额外配置
     config: Optional[Dict[str, Any]] = None
 
-    # 代理配置
-    proxy: Optional[Dict[str, Any]] = Field(default=None, description="代理配置")
+    # 代理配置（响应中密码已脱敏）
+    proxy: Optional[Dict[str, Any]] = Field(default=None, description="代理配置（密码已脱敏）")
 
     # 统计（从 Keys 聚合）
     total_keys: int = Field(default=0, description="总 Key 数量")