fix(page): preserve pre-maximize bounds across renderer maximize trip
The directed-IPC switch broke maximize-restore: main set bounds to the
work area before notifying the renderer, so doMaximize captured the
post-resize bounds as preMaximizeWindowBounds and doUnmaximize then
restored to the work area instead of the original size. Main now
threads the pre-maximize bounds through the maximize-request payload
and the renderer adopts those when present. Drag-out-of-maximize and
the toggle path inherit the fix because they read the same field.
Updates page-layout maximize coverage to drive via api.window.maximize
/ unmaximize (the page:maximize pubsub topic was retired in the same
directed-IPC pass).