Fix Windows crate 0.58 API compatibility

- Define XBUTTON1/XBUTTON2 constants (removed from windows crate)
- Update D3D11_CPU_ACCESS_FLAG usage
- Fix CreateTexture2D output parameter
- Fix BitBlt/EnumDisplayMonitors return type handling
- Fix encode_utf16 iterator usage

agent/src/input/keyboard.rs

@@ -81,9 +81,11 @@ impl KeyboardController {
     #[cfg(windows)]
     pub fn type_char(&mut self, ch: char) -> Result<()> {
         let mut inputs = Vec::new();
+        let mut buf = [0u16; 2];
+        let encoded = ch.encode_utf16(&mut buf);
 
         // For characters that fit in a single u16
-        for code_unit in ch.encode_utf16(&mut [0; 2]) {
+        for &code_unit in encoded {
             // Key down
             inputs.push(INPUT {
                 r#type: INPUT_KEYBOARD,