rsnix v0.5.0: graphics layer + cursor compositor

The first visible GUI surface: real rect primitives, a single
shadow→display push path, and an on-screen mouse cursor that can
never race the text surface.

gop:
- fill_rect + push_rect(x,y,w,h): every raster op rasterises into the
  RAM shadow, then push_rect copies the rect to the display (write-only,
  still never read) and composites the cursor on top. blit_glyph and
  scroll shifts now route through it.
- cursor overlay: 12x16 pointer (const-fn built from column lists) drawn
  white with a black offset outline; position in one AtomicU64 (x:high
  32, y:low 32) — unpack masks the low word (a bare 'as usize' cast is
  a no-op on 64-bit). The cursor never enters the shadow, so erasing is
  just a shadow push of the old rect.
- cursor_redraw after scroll shifts and once at spawn (the vt diff never
  re-blits idle cells).

cursor task (task 2, spawned at boot when a mouse is present):
- owns the PS/2 ring; polls every 10 ms, moves the cursor (clamped),
  tracks buttons, and forwards every event to a task's queue when
  'mouse <id>' armed it (the window-manager input path).
- /dev/mouse is now a position device (x/y/buttons snapshot); 'mouse'
  watches the cursor live (prints on change); 'cursor' prints one-shot
  state; 'gfx' draws a status-bar demo; 'gfx check' is an in-kernel
  pixel self-test (shadow readback, display readback, cursor overlay
  purity) — PASS/FAIL per stage.

Tests (headless QEMU + monitor injection):
- make test-gfx (new): all four compositor checks PASS.
- make test-mouse (rewritten): cursor tracks mouse_move deltas, buttons
  ride along, /dev/mouse snapshot, live watch, real-event queue routing.
- make test-msg: task numbering shifted (cursor is task 2; msgrecv is
  task 3) — updated, still PASS.
- make test-disk regression re-passes. 0 build warnings.

1 files changed, 19 insertions, 18 deletions

diff --git a/scripts/test-msg.sh b/scripts/test-msg.sh
index 0bd1c81..d81d8d7 100755
--- a/scripts/test-msg.sh
+++ b/scripts/test-msg.sh
@@ -93,20 +93,21 @@ echo $! >"$QPID"
 wait_log "$LOG" "boot: entering shell" 90 || fail "kernel never reached the shell"
 
 echo "==> 4/5 drive the shell (msgrecv / send / mouse routing / queue-full)"
+# msgrecv spawns as task 3 (task 2 is the cursor task).
 python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" \
         "msgrecv" \
-        "send 2 user 42" \
-        "send 2 timer" \
-        "send 2 key enter" \
-        "send 2 key ctrl-c" \
-        "send 2 key f3" \
-        "send 2 mouse 5 -3 3" \
+        "send 3 user 42" \
+        "send 3 timer" \
+        "send 3 key enter" \
+        "send 3 key ctrl-c" \
+        "send 3 key f3" \
+        "send 3 mouse 5 -3 3" \
         "sleep 800" \
         "jobs"
 
-# Real IRQ12 events through the queue: start routing to task 2, inject
+# Real IRQ12 events through the queue: start routing to task 3, inject
 # moves + a left press, stop.
-python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" "mouse 2"
+python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" "mouse 3"
 qemu_hmp "mouse_move 20 7"
 qemu_hmp "mouse_button 1"
 qemu_hmp "mouse_move -5 -3"
@@ -140,20 +141,20 @@ python3 "$SCRIPT_DIR/sendkeys.py" --sock "$SOCK" \
 echo "==> 5/5 wait for shutdown + verify"
 wait_qemu_exit 30 || fail "QEMU did not exit after poweroff"
 
-grep -aq "msgrecv: task 2 listening" "$LOG" || fail "msgrecv did not spawn"
-grep -aq "msgrecv\[2\]: User(42)" "$LOG" || fail "user message missing"
-grep -aq "msgrecv\[2\]: Timer" "$LOG" || fail "timer message missing"
-grep -aq "msgrecv\[2\]: Key(Enter)" "$LOG" || fail "key enter missing"
-grep -aq "msgrecv\[2\]: Key(Ctrl-c)" "$LOG" || fail "key ctrl-c missing"
-grep -aq "msgrecv\[2\]: Key(F3)" "$LOG" || fail "key f3 missing"
-grep -aq "msgrecv\[2\]: Mouse(+5,-3 L R)" "$LOG" || fail "synthesized mouse message missing"
+grep -aq "msgrecv: task 3 listening" "$LOG" || fail "msgrecv did not spawn"
+grep -aq "msgrecv\[3\]: User(42)" "$LOG" || fail "user message missing"
+grep -aq "msgrecv\[3\]: Timer" "$LOG" || fail "timer message missing"
+grep -aq "msgrecv\[3\]: Key(Enter)" "$LOG" || fail "key enter missing"
+grep -aq "msgrecv\[3\]: Key(Ctrl-c)" "$LOG" || fail "key ctrl-c missing"
+grep -aq "msgrecv\[3\]: Key(F3)" "$LOG" || fail "key f3 missing"
+grep -aq "msgrecv\[3\]: Mouse(+5,-3 L R)" "$LOG" || fail "synthesized mouse message missing"
 # Real IRQ12 events routed through the queue (button held across the move).
-grep -aq "msgrecv\[2\]: Mouse(+20,+7" "$LOG" || fail "real mouse move 20,7 not routed to queue"
-grep -aq "msgrecv\[2\]: Mouse(-5,-3 L" "$LOG" || fail "held-button routed move missing"
+grep -aq "msgrecv\[3\]: Mouse(+20,+7" "$LOG" || fail "real mouse move 20,7 not routed to queue"
+grep -aq "msgrecv\[3\]: Mouse(-5,-3 L" "$LOG" || fail "held-button routed move missing"
 grep -aq "queue full" "$LOG" || fail "17th send did not report queue full"
 grep -aq "send: unknown type" "$LOG" && fail "a bad send slipped through (expected none)"
 
 echo ""
 echo "PASS — message queues OK (all types, ordering, real-input routing, queue-full)"
 echo "  sent:     user · timer · key(enter,ctrl-c,f3) · mouse · 16+1 queue-full"
-echo "  routed:   mouse_move 20,7 → queue → msgrecv[2]"
+echo "  routed:   mouse_move 20,7 → queue → msgrecv[3]"