Schalter, Zeitfenster und Handoff-Prozent lagen im Usage-Monitor und mussten
in SettingsModalViewModel nur load->save durchgeschleift werden, damit ein
Settings-Speichern sie nicht zurueckwirft. Jetzt gehoeren sie dem General-Tab,
der Monitor ist wieder nur Anzeige + Threshold-Drag, und "Jetzt aktualisieren"
sitzt als Icon in der Titelleiste (neuer ModalShell.HeaderActions-Slot).
The diff viewer used ShowDialog at both call sites (task details, worktrees
overview), blocking navigation of the rest of the app while open. Switch both
to Window.Show(owner) and reuse the one open window (swap DataContext,
Activate()) instead of stacking a second one on re-open.
Add an opt-in maximize/restore button + double-click-titlebar toggle to
ModalShell (ShowMaximizeButton, default false so other modals are untouched),
wired on for DiffViewerView only. Reuses the existing Icon.WinMax/WinRestore
geometry and OffScreenMargin inset from MainWindow's own maximize handling.
The review gate (Approve & Merge locked until the diff is opened) already
fires DiffViewed before the dialog/window is shown, so it is unaffected by
the modal-to-non-modal change.
mika kuns