feat(client/input): desktop (absolute) mouse mode — remote-desktop sweep M1

New physical-mouse model beside capture: Desktop leaves the pointer
uncaptured and sends absolute positions through the letterbox
(MouseMoveAbs — every host injector already consumes it). Capture
stays the default and the game model.

- pf-client-core: MouseMode (capture|desktop) persisted in Settings,
  default capture so existing stores are unchanged.
- pf-presenter: Capture grows a desktop model — latest-wins pending
  abs position coalesced per loop iteration (same 1000 Hz discipline
  as relative), flushed before clicks/keys/wheel so they land where
  the cursor is; Ctrl+Alt+Shift+M flips the model live; local cursor
  stays hidden over the window (the host's composited cursor is the
  one you see until the M2 cursor channel); Windows keyboard grab
  only engages for capture (a desktop stream is something you
  Alt-Tab away from).
- gamescope gating: its EIS is relative-only, so desktop mode is
  pinned off there (resolved_compositor), with a log note.
- Settings surfaces: GTK row (dynamic caption), WinUI combo,
  console-UI row + step test, capture-hint line.

Verified: fmt + clippy -D warnings + tests (33/40/19) on Linux .21;
clippy -D warnings for all five crates incl. punktfunk-client-windows
native on .173.

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

clients/session/src/console.rs

@@ -158,6 +158,7 @@ pub fn run(target: Option<&str>) -> u8 {
             v => v,
         },
         touch_mode: settings_at_start.touch_mode(),
+        mouse_mode: settings_at_start.mouse_mode(),
         invert_scroll: settings_at_start.invert_scroll,
         json_status,
         on_connected: Some(Box::new(move |fingerprint: [u8; 32]| {

clients/session/src/main.rs

@@ -429,6 +429,7 @@ mod session_main {
                 v => v,
             },
             touch_mode: settings.touch_mode(),
+            mouse_mode: settings.mouse_mode(),
             invert_scroll: settings.invert_scroll,
             json_status: true,
             on_connected: Some(Box::new(|fingerprint: [u8; 32]| {