feat: initialise workspace — Milestone 1 asset explorer

Three-crate Cargo workspace structured per PROJECT.md spec:
- crates/sylpheed-formats  — Xbox 360 format parsers (no Bevy)
- crates/sylpheed-viewer   — Bevy 0.15 asset viewer + egui UI
- crates/sylpheed-cli      — CLI tools (extract/list/sniff/texture)

Milestone 1 features:
- XISO disc image reading via xdvdfs 0.8
- XPR2 texture container parsing + Morton de-tiling
- D3DFORMAT → wgpu TextureFormat mapping (DXT1/3/5, DXN, ARGB)
- Custom Bevy AssetLoader for .xpr files
- Orbit camera (LMB orbit, RMB pan, scroll zoom)
- egui file browser + RE notes panel
- CLI: extract / list / sniff / texture info / texture export
- GitHub Actions CI (Linux, macOS, Windows, WASM)
- Trunk WASM build config

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Cargo.toml

@@ -0,0 +1,50 @@
+[workspace]
+members = [
+    "crates/sylpheed-formats",
+    "crates/sylpheed-viewer",
+    "crates/sylpheed-cli",
+]
+resolver = "2"
+
+[workspace.package]
+version = "0.1.0"
+edition = "2021"
+license = "MIT OR Apache-2.0"
+authors = ["Project Sylpheed Reborn Contributors"]
+repository = "https://github.com/sylpheed-reborn/sylpheed-reborn"
+
+[workspace.dependencies]
+# ── Format / parser crates ──────────────────────────────────────────────────
+sylpheed-formats = { path = "crates/sylpheed-formats" }
+
+# ── Bevy game engine ────────────────────────────────────────────────────────
+bevy = { version = "0.15", default-features = false }
+bevy_egui = "0.31"
+
+# ── Xbox 360 XISO / XDVDFS disc image parsing ───────────────────────────────
+xdvdfs = { version = "0.8", features = ["log"] }
+
+# ── Binary format parsing with derive macros ────────────────────────────────
+binrw = "0.14"
+
+# ── Async runtime ────────────────────────────────────────────────────────────
+tokio = { version = "1", features = ["full"] }
+futures = "0.3"
+
+# ── Error handling ───────────────────────────────────────────────────────────
+thiserror = "2"
+anyhow = "1"
+
+# ── Logging ──────────────────────────────────────────────────────────────────
+tracing = "0.1"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
+
+# ── CLI ───────────────────────────────────────────────────────────────────────
+clap = { version = "4", features = ["derive"] }
+
+# ── Serialization ─────────────────────────────────────────────────────────────
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+
+# ── Async traits ──────────────────────────────────────────────────────────────
+async-trait = "0.1"