fix(bal): black bar on cancelled invalidation + editable fee follows dates (v0.3.6)

Two GUI fixes bundled together (v0.3.6):

- Fix #10 (black bar): in dialogs.py on_success_phase1, the cancelled
  invalidation branch no longer calls the blocking self.wait(3)+self.close().
  wait() uses time.sleep() and runs in the GUI thread, freezing the UI so the
  'Building Will' dialog could not repaint the area it just resized, leaving a
  black rectangle at the bottom. It now shows 'Aborted' plus the existing
  non-blocking Close button (_add_close_button), consistent with the other
  end-of-flow branches.

- Fix #11 (editable fee): in widgets.py WillSettingsWidget.apply_editable_dates,
  the fee widget (baltx_fees) now follows the same 'Editable dates' setting as
  the locktime/threshold widgets (set_read_only(not editable_dates)) instead of
  being forced read-only. With the setting ticked, dates AND fee are editable
  outside the wizard; unticked, all three are read-only. Default stays OFF.

Version bumped 0.3.5 -> 0.3.6 (manifest.json, __init__.py, plugin_base.py,
VERSION). CHANGELOG: entries #10 and #11. ruff clean; full suite 239 passed.

bal/gui/qt/widgets.py

@@ -705,13 +705,15 @@ class WillSettingsWidget(QWidget):
         self.apply_editable_dates()
 
     def apply_editable_dates(self):
-        """Re-read the EDITABLE_DATES setting and lock/unlock the date fields.
+        """Re-read the EDITABLE_DATES setting and lock/unlock the editable fields.
 
         Outside the "Build your will" wizard (``read_only=True``) the
-        delivery-time and check-alive dates are display-only by default. When
-        the user ticks "Editable dates" in the settings they become editable
-        here too. The fee field always stays read-only outside the wizard,
-        because C2 only concerns the dates.
+        delivery-time, check-alive dates AND the mining fee are display-only by
+        default. When the user ticks "Editable dates" in the settings, all three
+        fields (locktime, threshold and fee) become editable here too; when it
+        is unticked they all go back to read-only. The fee follows exactly the
+        same rule as the dates (it used to stay always read-only, but the user
+        asked for the fee to be editable together with the dates).
 
         This is safe to call repeatedly: it only adjusts the read-only state of
         the already-created sub-widgets, it does not rebuild anything. It is the
@@ -732,7 +734,9 @@ class WillSettingsWidget(QWidget):
 
         self.widgets["locktime"].set_read_only(not editable_dates)
         self.widgets["threshold"].set_read_only(not editable_dates)
-        self.widgets["baltx_fees"].set_read_only(True)
+        # The fee now follows the very same "Editable dates" rule as the dates:
+        # editable outside the wizard only when the setting is ticked.
+        self.widgets["baltx_fees"].set_read_only(not editable_dates)
 
     def create_alarms(self, alarm_start, alarm_end):
         """Build the VALARM reminder blocks for the .ics event (Group D / D1).