* fix(macos): stop Canvas presents from stealing focus
Agent-driven canvas.present/canvas.navigate activated the app with
NSApp.activate(ignoringOtherApps:), yanking keyboard focus from
whatever the user was doing. The Canvas panel's elevated window level
already keeps it visible without app activation, and user entry points
(AppNavigationActions) activate explicitly, so presentation now orders
the panel front without switching apps.
* fix(macos): order Canvas front without taking key focus
* fix(macos): drop showWindow from Canvas window presentation
* fix(macos): keep Canvas hidden for agent content operations
Agent canvas.evalJS, canvas.snapshot, and canvas.a2ui.* commands routed
through CanvasManager.show, which re-presented the panel and called
NSApp.activate(ignoringOtherApps:) on every content update. After a
gateway restart the hosted A2UI page is dead, so the next agent push
always re-opened a panel the user had closed and stole focus.
Content operations now use a non-presenting ensureController/prepare
path; only canvas.present, canvas.navigate, and user actions reveal the
panel. Snapshot is read-only: it requires a visible matching panel and
returns CANVAS_HIDDEN instead of mutating panel state (WebKit cannot
render ordered-out windows).
* chore(i18n): refresh native inventory line offsets
