fix: guard tkinter/matplotlib imports for headless CI environments

9_Firmware/9_3_GUI/GUI_V65_Tk.py

@@ -44,6 +44,7 @@ from typing import ClassVar
 
 import numpy as np
 
+try:
     import tkinter as tk
     from tkinter import ttk, filedialog
 
@@ -52,6 +53,10 @@ matplotlib.use("TkAgg")
     from matplotlib.figure import Figure
     from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
 
+    _HAS_GUI = True
+except (ModuleNotFoundError, ImportError):
+    _HAS_GUI = False
+
 # Import protocol layer (no GUI deps)
 from radar_protocol import (
     RadarProtocol, FT2232HConnection,