Initial commit: xenia-rs workspace for Xbox 360 RE

Rust reimplementation of the xenia Xbox 360 emulator targeting reverse-
engineering and preservation, initially scoped to Project Sylpheed.

Includes:
- XEX2 loader (LZX decompression, AES decryption, PE parsing)
- XISO / XGD2 disc image VFS
- PPC interpreter with 200+ opcodes and VMX128 decoding
- Static analyzer: functions, cross-references, labels, asm + SQLite output
- HLE kernel covering the xboxkrnl/xam subset used by Sylpheed init
- Debugger with in-memory and SQLite-backed execution tracing
- `xenia-rs` CLI with extract/dis/exec commands that produce cumulative,
  superset SQLite databases and opt-in instruction/import/branch traces

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/xenia-hid/src/lib.rs

@@ -0,0 +1,47 @@
+/// Human input device system stub.
+pub struct InputSystem {
+    pub gamepad: GamepadState,
+}
+
+#[derive(Default, Clone, Copy)]
+pub struct GamepadState {
+    pub buttons: u16,
+    pub left_trigger: u8,
+    pub right_trigger: u8,
+    pub left_stick_x: i16,
+    pub left_stick_y: i16,
+    pub right_stick_x: i16,
+    pub right_stick_y: i16,
+}
+
+/// Xbox 360 button flags
+pub mod buttons {
+    pub const DPAD_UP: u16 = 0x0001;
+    pub const DPAD_DOWN: u16 = 0x0002;
+    pub const DPAD_LEFT: u16 = 0x0004;
+    pub const DPAD_RIGHT: u16 = 0x0008;
+    pub const START: u16 = 0x0010;
+    pub const BACK: u16 = 0x0020;
+    pub const LEFT_THUMB: u16 = 0x0040;
+    pub const RIGHT_THUMB: u16 = 0x0080;
+    pub const LEFT_SHOULDER: u16 = 0x0100;
+    pub const RIGHT_SHOULDER: u16 = 0x0200;
+    pub const A: u16 = 0x1000;
+    pub const B: u16 = 0x2000;
+    pub const X: u16 = 0x4000;
+    pub const Y: u16 = 0x8000;
+}
+
+impl InputSystem {
+    pub fn new() -> Self {
+        Self {
+            gamepad: GamepadState::default(),
+        }
+    }
+}
+
+impl Default for InputSystem {
+    fn default() -> Self {
+        Self::new()
+    }
+}