Replace the top icon-button bar in SettingsView with a grouped left
QTreeWidget: Application, Cards and Data, Chat and Sound, Advanced. The
active page is the selected row (palette highlight); search mode hides
the tree; group headers expand but never select. Page tr() contexts
stay DlgSettings; new group names are SettingsView strings.
Reworked to stay in the enlarged modal instead of the settings tab.
Keep settings modal per review: size to ~90% of the main window
(5% margins each side) with screen fallback, size grip and
750x700 minimum bounded to the screen. Drops the tab approach
while giving dense pages room without the tab-switch friction.
Move the search bar, tab bar, stacked pages and search results out of
DlgSettings into a reusable SettingsView widget. The dialog becomes a
thin frame (title, OK button, close validation) delegating to the view.
No visual or behavior change; tr() contexts preserved as DlgSettings.
