fix: hide + freeze the local cursor while streaming

The host renders its own cursor from our raw deltas, so the local macOS cursor both
stays visible and drifts away from the remote one — and it can wander out of the window,
where a click focuses another app. While the stream has focus, do what Moonlight does:
warp the cursor mid-view, disconnect it from mouse movement
(CGAssociateMouseAndMouseCursorPosition(false) — GCMouse still delivers raw HID deltas),
and hide it. Released on app deactivation (Cmd+Tab is the escape hatch), view teardown,
and disconnect; re-captured when the stream regains focus. The HUD's Disconnect gains ⌘D
since a hidden, frozen cursor can't click it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

clients/apple/README.md

@@ -103,9 +103,12 @@ PUNKTFUNK_AUTOCONNECT=<box-ip> PUNKTFUNK_MODE=1280x720x60 swift run PunktfunkCli
    doesn't persist fingerprints yet — add it alongside the "add host" UX.
 8. **Input capture caveats** (stage 1): GC handlers only fire while the app has focus —
    on focus loss `InputCapture` auto-releases everything still held (keys + buttons) so
-   nothing sticks down host-side. Local shortcuts (⌘-anything) still also reach the host;
-   a capture toggle is a small follow-up. One live capture per process (the GC mouse/
-   keyboard singletons have a single handler slot — ownership is tracked so a stale
+   nothing sticks down host-side. While the stream has focus the LOCAL cursor is hidden
+   and frozen mid-view (`CursorCapture` in StreamView.swift — the host renders its own
+   cursor; the local one diverges from it and a stray click would focus another app);
+   Cmd+Tab frees it, ⌘D disconnects. Local shortcuts (⌘-anything) still also reach the
+   host; a capture toggle is a small follow-up. One live capture per process (the GC
+   mouse/keyboard singletons have a single handler slot — ownership is tracked so a stale
    capture's stop() can't clobber a newer one).
 9. **iOS**: same package (`BUILD_IOS=1` for the xcframework slice); `StreamView` needs the
    `UIViewRepresentable` twin and touch→input mapping.