refactor: Introduce accumulate_usage function for token aggregation, enhance alias map expansion in BatchProcessor, and streamline error handling in PreclassificationService. Update PDF processing utilities for improved image conversion and error logging.

gui/tabs/metrics_tab.py

@@ -3,8 +3,11 @@ import customtkinter as ctk
 import tkinter.ttk as ttk
 from gui.styles import AppStyles
 
-# matplotlib es opcional
+# matplotlib y numpy son opcionales
 try:
+  import matplotlib
+  matplotlib.use("Agg")  # backend no interactivo para render en canvas Tk
+  import numpy as np
   from matplotlib.figure import Figure
   from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
   HAS_MPL = True
@@ -226,7 +229,6 @@ class MetricsTab:
             extract_vals = [input_extract, cached_extract, output_extract]
             norm_vals = [input_norm, cached_norm, output_norm]
             
-            import numpy as np
             x = np.arange(len(labels))
             width = 0.35