Windowed GUI: wm module, input routing, and the paint app

- Add the wm window-manager facility per ADR 0004: overlapping
  pixel-surface windows, damage-rectangle compositing, WM-drawn title
  bar, focus/minimize/close, and F1-F4 keybindings
- Add gop shadow compositing primitives and vt::repaint_region so the
  console stays layer 0 beneath windows
- Route mouse (absolute coords, press/release edges) and keyboard
  (focus-aware input pump) to the focused window
- Add the rspaint drawing-program crate (pen, 8 colors, clear) and shell
  draw/windows/restore commands
- Extend TaskMsg with AppMouse/Focus/Close and document the design in
  CONTEXT.md + ADR 0004

1 files changed, 17 insertions, 2 deletions

diff --git a/rsnix/src/cursor.rs b/rsnix/src/cursor.rs
index 31b919e..b986b23 100644
--- a/rsnix/src/cursor.rs
+++ b/rsnix/src/cursor.rs
@@ -49,14 +49,29 @@ fn forward_target() -> Option<usize> {
 }
 
 fn task_main() {
+    let mut prev_buttons: u8 = 0;
     loop {
         while let Some(ev) = crate::usb::poll_mouse()
             .or_else(crate::ehci::poll_mouse)
             .or_else(crate::uhci::poll_mouse)
             .or_else(crate::ps2::try_poll_mouse)
         {
-            crate::gop::cursor_move(ev.dx, ev.dy);
-            crate::gop::cursor_set_buttons(btn_bits(&ev));
+            let (cx, cy) = crate::gop::cursor_move(ev.dx, ev.dy);
+            let buttons = btn_bits(&ev);
+            crate::gop::cursor_set_buttons(buttons);
+            // Left-button edge detection → press/release.
+            let kind = if buttons & 1 != 0 && prev_buttons & 1 == 0 {
+                crate::ps2::MouseKind::Press
+            } else if buttons & 1 == 0 && prev_buttons & 1 != 0 {
+                crate::ps2::MouseKind::Release
+            } else {
+                crate::ps2::MouseKind::Move
+            };
+            prev_buttons = buttons;
+            // Route to the window manager (focus + deliver to the focused
+            // window with window-relative coordinates).
+            crate::wm::route_mouse(cx as i32, cy as i32, buttons, kind);
+            // Legacy single-target debug routing (`mouse <id>`).
             if let Some(id) = forward_target()
                 && crate::sched::send(id, TaskMsg::Mouse(ev)).is_err()
             {