feat: enhance control text processing in VoxCPMDemo

Added regex to strip parentheses from control instructions in the text synthesis method to ensure compatibility with the expected prompt format. This change improves the robustness of the input handling.

app.py

@@ -1,4 +1,5 @@
 import os
+import re
 import sys
 import logging
 import numpy as np
@@ -290,6 +291,9 @@ class VoxCPMDemo:
             raise ValueError("Please input text to synthesize.")
 
         control = (control_instruction or "").strip()
+        # Strip any parentheses (half-width/full-width) from control text to avoid
+        # breaking the "(control)text" prompt format expected by the model.
+        control = re.sub(r"[()（）]", "", control).strip()
         final_text = f"({control}){text}" if control else text
 
         audio_path = reference_wav_path_input if reference_wav_path_input else None