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/linux/src/ui_settings.rs

@@ -69,6 +69,14 @@ const TOUCH_MODE_CAPTIONS: &[&str] = &[
     "The cursor jumps to your finger — a tap clicks there",
     "Real multi-touch reaches the host — for touch-native apps",
 ];
+/// Physical-mouse model values (persisted) + labels + dynamic captions — same idiom as
+/// the touch rows. Ctrl+Alt+Shift+M flips the model live in-stream.
+const MOUSE_MODES: &[&str] = &["capture", "desktop"];
+const MOUSE_MODE_LABELS: &[&str] = &["Capture (games)", "Desktop (absolute)"];
+const MOUSE_MODE_CAPTIONS: &[&str] = &[
+    "Pointer locks to the stream — relative motion, best for games",
+    "Pointer moves freely in and out — best for remote desktop work",
+];
 
 /// punktfunk's own license (MIT OR Apache-2.0), shown on the About dialog's Legal page.
 const APP_LICENSE: &str = concat!(
@@ -542,6 +550,20 @@ pub fn show(
             set_row_subtitle(&w, TOUCH_MODE_CAPTIONS[i]);
         });
     }
+    let mouse_row = ChoiceRow::new(
+        &dialog,
+        inline,
+        "Mouse input",
+        MOUSE_MODE_CAPTIONS[0],
+        MOUSE_MODE_LABELS,
+    );
+    {
+        let w = mouse_row.widget().clone();
+        mouse_row.connect_changed(move |i| {
+            let i = (i as usize).min(MOUSE_MODE_CAPTIONS.len() - 1);
+            set_row_subtitle(&w, MOUSE_MODE_CAPTIONS[i]);
+        });
+    }
     let inhibit_row = adw::SwitchRow::builder()
         .title("Capture system shortcuts")
         .subtitle("Forward Alt+Tab, Super, … to the host while input is captured")
@@ -718,6 +740,12 @@ pub fn show(
         touch_row.set_selected(touch_i as u32);
         // set_selected never fires the changed hook, so seed the dynamic caption directly.
         set_row_subtitle(touch_row.widget(), TOUCH_MODE_CAPTIONS[touch_i]);
+        let mouse_i = MOUSE_MODES
+            .iter()
+            .position(|&m| m == s.mouse_mode)
+            .unwrap_or(0);
+        mouse_row.set_selected(mouse_i as u32);
+        set_row_subtitle(mouse_row.widget(), MOUSE_MODE_CAPTIONS[mouse_i]);
         let comp_i = COMPOSITORS
             .iter()
             .position(|&c| c == s.compositor)
@@ -788,6 +816,7 @@ pub fn show(
     touch_group.add(touch_row.widget());
     // Group titles are Pango markup — the ampersand must be an entity.
     let kbm_group = group("Keyboard & mouse", "");
+    kbm_group.add(mouse_row.widget());
     kbm_group.add(&inhibit_row);
     kbm_group.add(&invert_row);
     input.add(&touch_group);
@@ -867,6 +896,8 @@ pub fn show(
         }
         s.touch_mode =
             TOUCH_MODES[(touch_row.selected() as usize).min(TOUCH_MODES.len() - 1)].to_string();
+        s.mouse_mode =
+            MOUSE_MODES[(mouse_row.selected() as usize).min(MOUSE_MODES.len() - 1)].to_string();
         s.forward_pad = chosen_pin.borrow().clone();
         s.compositor = COMPOSITORS[(compositor_row.selected() as usize).min(COMPOSITORS.len() - 1)]
             .to_string();

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]| {

clients/windows/src/app/settings.rs

@@ -90,6 +90,13 @@ const TOUCH_MODES: &[(&str, &str)] = &[
     ("pointer", "Direct pointer"),
     ("touch", "Touch passthrough"),
 ];
+/// Physical-mouse presets: `(stored value, display label)` — capture (pointer lock,
+/// relative, for games) vs desktop (uncaptured absolute pointer, for remote desktop
+/// work). Ctrl+Alt+Shift+M flips the model live in-stream.
+const MOUSE_MODES: &[(&str, &str)] = &[
+    ("capture", "Capture (games)"),
+    ("desktop", "Desktop (absolute)"),
+];
 /// Host compositor presets: `(stored value, display label)`. Advisory — the host falls back to
 /// auto-detect when the choice is unavailable. Only meaningful against a Linux host.
 const COMPOSITORS: &[(&str, &str)] = &[
@@ -394,6 +401,10 @@ pub(crate) fn settings_page(
     let touch_combo = setting_combo(ctx, "Touch input", touch_names, touch_i, |s, i| {
         s.touch_mode = TOUCH_MODES[i].0.to_string();
     });
+    let (mouse_names, mouse_i) = presets(MOUSE_MODES, |v| *v == s.mouse_mode);
+    let mouse_combo = setting_combo(ctx, "Mouse input", mouse_names, mouse_i, |s, i| {
+        s.mouse_mode = MOUSE_MODES[i].0.to_string();
+    });
     let invert_scroll_toggle =
         setting_toggle(ctx, "Invert scroll direction", s.invert_scroll, |s, on| {
             s.invert_scroll = on
@@ -542,6 +553,13 @@ pub(crate) fn settings_page(
             out.extend(group(
                 Some("Keyboard & mouse"),
                 vec![
+                    described(
+                        mouse_combo,
+                        "Capture locks the pointer to the stream and sends relative motion — \
+                         best for games. Desktop leaves the pointer free to enter and leave \
+                         the stream and sends absolute positions — best for remote desktop \
+                         work. Ctrl+Alt+Shift+M switches live.",
+                    ),
                     described(
                         shortcuts_toggle,
                         "Alt+Tab, the Windows key and friends reach the host while the stream \