rsnix v0.5.1: force the GUI canvas to 800x600 via GOP SetMode

The kernel used to inherit whatever GOP mode the firmware picked
(QEMU/OVMF gave 1280x800). Now every surface derives from a fixed
800x600 canvas:

- uefi: typed EfiGopQueryMode/SetMode/GetMode fn pointers in
  GraphicsOutputProtocol (were raw *mut c_void, never called).
- gop::select_gop_mode: scan the mode list for an exact 800x600
  (32-bit BGR/RGB only, the driver assumes 4 Bpp), SetMode it; fall
  back to the smallest mode that fits the canvas, then to the
  firmware's choice. SetMode may move both the mode info pointer and
  the framebuffer base, so both are re-read after the switch. Boot
  log: 'gop: mode 3 selected — 800x600 (was 1280x800)'.
- tests: relative assertions are resolution-agnostic; test-gfx and
  test-mouse had a boot-log race (shell line prints before the cursor
  task line) — now wait for the cursor line instead of grepping once.
  All four suites pass at 800x600. 0 build warnings.

1 files changed, 19 insertions, 3 deletions

diff --git a/rsnix/src/uefi.rs b/rsnix/src/uefi.rs
index f947c90..c311ad9 100644
--- a/rsnix/src/uefi.rs
+++ b/rsnix/src/uefi.rs
@@ -321,12 +321,28 @@ pub struct GopMode {
 
 #[repr(C)]
 pub struct GraphicsOutputProtocol {
-    pub query_mode: *mut c_void,
-    pub set_mode: *mut c_void,
-    pub get_current_mode: *mut c_void,
+    pub query_mode: EfiGopQueryMode,
+    pub set_mode: EfiGopSetMode,
+    pub get_current_mode: EfiGopGetMode,
     pub mode: *mut GopMode,
 }
 
+pub type EfiGopQueryMode = unsafe extern "efiapi" fn(
+    *mut GraphicsOutputProtocol,
+    u32,                   // mode number
+    *mut usize,            // out: size of info
+    *mut *mut GopModeInfo, // out: info pointer (firmware-owned)
+) -> Status;
+
+pub type EfiGopSetMode = unsafe extern "efiapi" fn(*mut GraphicsOutputProtocol, u32) -> Status;
+
+pub type EfiGopGetMode = unsafe extern "efiapi" fn(
+    *mut GraphicsOutputProtocol,
+    *mut u32,              // out: current mode
+    *mut u32,              // out: size of info
+    *mut *mut GopModeInfo, // out: info pointer
+) -> Status;
+
 // ---------------------------------------------------------------------------
 // System table
 // ---------------------------------------------------------------------------