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, 1 insertions, 0 deletions

diff --git a/shell/Cargo.toml b/shell/Cargo.toml
index bc35524..f95b574 100644
--- a/shell/Cargo.toml
+++ b/shell/Cargo.toml
@@ -9,3 +9,4 @@ workspace = true
 [dependencies]
 rsnix = { path = "../rsnix" }
 rsdosedit = { path = "../rsdosedit" }
+rspaint = { path = "../rspaint" }