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>

Trunk.toml

@@ -0,0 +1,23 @@
+# Trunk.toml
+# Trunk is the WASM bundler for Bevy/Rust web builds.
+# Install: cargo install trunk
+# Dev server: trunk serve
+# Production build: trunk build --release
+
+[build]
+# Entry point HTML file
+target = "crates/sylpheed-viewer/index.html"
+# Output directory
+dist = "dist"
+# Public URL path (change to "/sylpheed/" if hosting in a subdirectory)
+public_url = "/"
+
+[watch]
+# Rebuild on changes in these paths
+paths = ["crates/", "assets/"]
+# Ignore these paths
+ignore = ["dist/", "target/"]
+
+[serve]
+port = 8080
+open = false