Preferences: toggle slot numbers on wiresheet, off by default

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

main.py

@@ -2711,6 +2711,17 @@ def open_preferences_dialog():
     )
     chk_lazy_loading.grid(row=6, column=1, sticky="w", pady=(0, 15))
 
+    lbl_slot_numbers = ttk.Label(frame_padded, text="Slot numbers on wiresheet?", anchor="w")
+    lbl_slot_numbers.grid(row=7, column=0, sticky="w", pady=(0, 15), padx=(0, 10))
+
+    var_slot_numbers = tk.BooleanVar(value=app_state.SHOW_SLOT_NUMBERS)
+    chk_slot_numbers = ttk.Checkbutton(
+        frame_padded,
+        text="Yes",
+        variable=var_slot_numbers
+    )
+    chk_slot_numbers.grid(row=7, column=1, sticky="w", pady=(0, 15))
+
     def apply_preferences():
         try:
             val = int(entry_grid.get().strip())
@@ -2768,6 +2779,7 @@ def open_preferences_dialog():
             app_state.ADD_TIMESTAMP = var_timestamp.get()
             app_state.TRACE_DASP = var_trace_dasp.get()
             app_state.LAZY_LOADING = var_lazy_loading.get()
+            app_state.SHOW_SLOT_NUMBERS = var_slot_numbers.get()
             app_state.SEDONA_HOME = entry_home.get().strip()
 
             app_state.save_preferences()
@@ -2786,7 +2798,7 @@ def open_preferences_dialog():
             messagebox.showerror("Invalid Input", message, parent=dialog)
 
     btn_save_pref = ttk.Button(frame_padded, text="Apply Changes", command=apply_preferences)
-    btn_save_pref.grid(row=7, column=1, sticky="e")
+    btn_save_pref.grid(row=8, column=1, sticky="e")
 
     if not app_state.SEDONA_HOME:
         entry_home.focus_set()