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, 20 insertions, 0 deletions

diff --git a/rsnix/src/ps2.rs b/rsnix/src/ps2.rs
index 965e4a0..cac476f 100644
--- a/rsnix/src/ps2.rs
+++ b/rsnix/src/ps2.rs
@@ -463,6 +463,26 @@ pub struct MouseEvent {
     pub middle: bool,
 }
 
+/// What happened in a window-relative (GUI) mouse event.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+pub enum MouseKind {
+    Move,
+    Press,
+    Release,
+}
+
+/// A mouse event delivered to a focused GUI window: absolute coordinates
+/// relative to the window's content top-left, the current button bitmask,
+/// and the action (move / press / release).  Unlike `MouseEvent` (relative
+/// deltas), this is what an app's drawing loop consumes.
+#[derive(Clone, Copy, Debug)]
+pub struct AppMouseEvent {
+    pub x: i32,
+    pub y: i32,
+    pub buttons: u8,
+    pub kind: MouseKind,
+}
+
 /// Packet assembly state — lives in main context (consumer side), fed by
 /// the raw byte ring that the IRQ12 handler fills.
 struct MouseState {