Update README documentation to clarify auth-dir configuration for Windows users

- Added a note for setting `auth-dir` on Windows systems in both English and Chinese README files.
- Improved descriptions for existing configuration options.

Address Qwen3 tool injection issue to prevent random token insertions

- Modify Qwen client to insert a placeholder tool when none is defined, avoiding erratic behavior in streaming responses.

internal/api/handlers/openai/openai_handlers.go

@@ -483,7 +483,7 @@ outLoop:
 			// Handle client disconnection.
 			case <-c.Request.Context().Done():
 				if c.Request.Context().Err().Error() == "context canceled" {
-					log.Debugf("qwen client disconnected: %v", c.Request.Context().Err())
+					log.Debugf("openai client disconnected: %v", c.Request.Context().Err())
 					cliCancel() // Cancel the backend request.
 					return
 				}