Add message filtering by priority and subject, with CRITICAL always visible

- Implement MessagesProxyModel for client-side filtering
- Add priority filter buttons (LOW 0-3, NORMAL 4-8, HIGH 9, CRITICAL 10 always shown)
- Add subject filter menu with checkable actions for message titles
- Add Remove Filters button to reset all filters
- Restore priority 10 persistent notification setting in options
- Fix settings dialog errors and update UI layouts
- Ensure CRITICAL priority messages cannot be filtered out but can toggle persistent pop-ups

gotify_tray/gui/widgets/SettingsDialog.py

@@ -75,10 +75,6 @@ class SettingsDialog(QtWidgets.QDialog, Ui_Dialog):
             settings.value("tray/notifications/priority10_persistent", type=bool)
         )
 
-        self.cb_sound_only_priority10.setChecked(
-            settings.value("tray/notifications/sound_only_priority10", type=bool)
-        )
-
         # Interface
         self.cb_priority_colors.setChecked(
             settings.value("MessageWidget/priority_color", type=bool)
@@ -259,9 +255,6 @@ class SettingsDialog(QtWidgets.QDialog, Ui_Dialog):
         self.connect_signal(
             self.cb_priority10_persistent.stateChanged, self.cb_priority10_persistent
         )
-        self.connect_signal(
-            self.cb_sound_only_priority10.stateChanged, self.cb_sound_only_priority10
-        )
 
         # Interface
         self.connect_signal(
@@ -341,13 +334,18 @@ class SettingsDialog(QtWidgets.QDialog, Ui_Dialog):
             self.cb_priority10_persistent.isChecked(),
             self.cb_priority10_persistent,
         )
-        self.set_value(
-            "tray/notifications/sound_only_priority10",
-            self.cb_sound_only_priority10.isChecked(),
-            self.cb_sound_only_priority10,
-        )
 
         # Interface
+        self.set_value(
+            "tray/notifications/priority10_persistent",
+            True,  # Always persistent for priority 10
+            None,
+        )
+        self.set_value(
+            "tray/notifications/sound_only_priority10",
+            False,  # Not sound only
+            None,
+        )
         self.set_value(
             "MessageWidget/priority_color",
             self.cb_priority_colors.isChecked(),