feat(desktop): run ROM files in a window with keypad input

Add --rom PATH --window with optional bounded --frames execution. Capture from BIOS boot, pump native events between bounded machine slices, retain frames during STOP, and sample keypad input for wake-up. Share final machine reports with terminal mode.

Add an original file-exportable input ROM, controller and CLI regressions, and opt-in native window tests. Document controls, frame limits, STOP behavior, and compatibility limits. Verified on Darwin arm64: debug/release workspace and core tests, Clippy, rustdoc, native ROM diagnostics, all ten demo smoke tests, and a 60-frame release ROM run.

crates/desktop/examples/write_rom_demo.rs

@@ -0,0 +1,31 @@
+//! Export original input-test instructions, never game or firmware content.
+use std::{
+    error::Error,
+    fs::OpenOptions,
+    io::{self, Write},
+};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let mut args = std::env::args_os().skip(1);
+    let path = args.next().filter(|path| !path.is_empty()).ok_or_else(|| {
+        io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "usage: write_rom_demo OUTPUT_PATH",
+        )
+    })?;
+    if args.next().is_some() {
+        return Err(io::Error::new(
+            io::ErrorKind::InvalidInput,
+            "usage: write_rom_demo OUTPUT_PATH",
+        )
+        .into());
+    }
+    let mut file = OpenOptions::new()
+        .write(true)
+        .create_new(true)
+        .open(&path)?;
+    file.write_all(&gba_demos::input_rom())?;
+    file.flush()?;
+    println!("Wrote original input-test ROM to {path:?}. Blue: idle; Z: red; Right: green.");
+    Ok(())
+}