[GameSelector] Persist quick-filter toolbar edits and repair filter settings migration (#7500)

* [GameSelector] Persist quick-filter toolbar edits and repair filter settings migration

- Save game-filter parameters on toolbar changes, debounced with flush on close
- Repair pre-camelCase gamefilters.ini keys in place on startup
- Map the legacy creator-name filter to hostNameFilter
- Balance begin/endFilterChange in GamesProxyModel::refresh
- Align the hideIgnoredUserGames default between model and settings
- Cover the migration with regression tests

* [Review] Address RickyRister comments on filter persistence

- Rename game-type prefix constants to SCREAMING_SNAKE to match
  MIGRATION_SENTINEL_KEY and project style
- Document why GameSelector destructor flushes a pending debounced
  filter save (toolbar path has no other writer)

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

cockatrice/src/interface/widgets/server/games_model.cpp

@@ -523,6 +523,9 @@ bool GamesProxyModel::filterAcceptsRow(int sourceRow) const
 
 void GamesProxyModel::refresh()
 {
+#if (QT_VERSION >= QT_VERSION_CHECK(6, 9, 0))
+    beginFilterChange();
+#endif
 #if (QT_VERSION >= QT_VERSION_CHECK(6, 10, 0))
     endFilterChange(QSortFilterProxyModel::Direction::Rows);
 #else