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-vfs/src/lib.rs

@@ -0,0 +1,33 @@
+pub mod device;
+pub mod disc_image;
+
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum VfsError {
+    #[error("I/O error: {0}")]
+    Io(#[from] std::io::Error),
+
+    #[error("Invalid format: {0}")]
+    InvalidFormat(String),
+
+    #[error("File not found: {0}")]
+    NotFound(String),
+}
+
+/// A virtual filesystem entry (file or directory).
+#[derive(Debug)]
+pub struct VfsEntry {
+    pub name: String,
+    pub is_directory: bool,
+    pub size: u64,
+    pub offset: u64,
+}
+
+/// Trait for VFS device implementations (XISO, STFS, host path, etc.)
+pub trait VfsDevice: Send + Sync {
+    fn name(&self) -> &str;
+    fn list_root(&self) -> Result<Vec<VfsEntry>, VfsError>;
+    fn read_file(&self, path: &str) -> Result<Vec<u8>, VfsError>;
+    fn stat(&self, path: &str) -> Result<VfsEntry, VfsError>;
+}