Allow renaming profile tabs outside Programmiermodus

Double-click-to-rename already existed but silently no-op'd unless
Programmiermodus was on, and even there it only updated the in-memory
self.combined without saving -- the name was lost unless some later button
edit happened to trigger an autosave. Since profile_names lives purely in
the combined JSON and never touches the board, there's no reason to gate it
behind the heavier editing mode: it now works from any mode, loading/saving
the combined file directly (auto-creating it if needed) when not already in
an active Programmiermodus session, and always persists immediately.

(cherry picked from commit 82c3fd0056)

desktop_viewer.py

@@ -254,14 +254,37 @@ class VersaPadViewer(tk.Tk):
             btn.configure(text=names[p])
 
     def _rename_tab(self, profile):
-        if not self.editing.get() or self.combined is None:
-            return
-        current = self.combined["profile_names"][profile]
+        """Profilname per Doppelklick auf den Tab umbenennen -- geht in
+        jedem Modus (rein lokal, landet nie aufs Board, siehe Kritische
+        Domänenregeln). Im Programmiermodus wird der bereits geladene
+        In-Memory-State direkt bearbeitet + autosaved; sonst wird die
+        kombinierte Datei frisch gelesen/geschrieben (legt sie bei Bedarf
+        automatisch an, siehe versapad_combined.load_or_fetch())."""
+        if self.editing.get() and self.combined is not None:
+            combined = self.combined
+        else:
+            try:
+                combined = vcomb.load_or_fetch()
+            except (OSError, ValueError, KeyError) as e:
+                messagebox.showerror("Umbenennen fehlgeschlagen", str(e))
+                return
+
+        current = combined["profile_names"][profile]
         name = simpledialog.askstring("Profil umbenennen", "Neuer Name (nur lokal, nicht aufs Board):",
                                       initialvalue=current, parent=self)
-        if name:
-            self.combined["profile_names"][profile] = name
-            self._update_tab_labels()
+        if not name:
+            return
+        combined["profile_names"][profile] = name
+
+        if combined is self.combined:
+            self._autosave_combined()
+        else:
+            try:
+                vcomb.save_file(combined, vcomb.DEFAULT_PATH)
+            except OSError as e:
+                messagebox.showerror("Umbenennen fehlgeschlagen", f"Speichern fehlgeschlagen: {e}")
+                return
+        self._update_tab_labels()
 
     def _show_mcp_info(self):
         win = tk.Toplevel(self)