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>

justfile

@@ -0,0 +1,101 @@
+# Justfile — project-wide build and dev commands
+# Install with: cargo install just
+# Usage: just <recipe>
+
+# Default: list all recipes
+default:
+    @just --list
+
+# ── Setup ──────────────────────────────────────────────────────────────────────
+
+# Install all required tools
+setup:
+    @echo "Installing build tools..."
+    cargo install trunk          # WASM bundler
+    cargo install wasm-bindgen-cli
+    rustup target add wasm32-unknown-unknown
+    @echo "All tools installed!"
+
+# ── Native builds ──────────────────────────────────────────────────────────────
+
+# Run the asset viewer (native, debug)
+run:
+    cargo run --bin sylpheed-viewer
+
+# Run with hot-reloading enabled (faster iteration)
+run-dev:
+    cargo run --bin sylpheed-viewer --features sylpheed-viewer/dev
+
+# Build native release
+build-native:
+    cargo build --release --bin sylpheed-viewer
+
+# Run the CLI
+cli *ARGS:
+    cargo run --bin sylpheed-cli -- {{ARGS}}
+
+# ── WASM / Web builds ──────────────────────────────────────────────────────────
+
+# Start WASM dev server with hot-reload
+web:
+    trunk serve
+
+# Build WASM release bundle (output in ./dist/)
+build-web:
+    trunk build --release
+
+# ── Extraction shortcuts ───────────────────────────────────────────────────────
+
+# Extract an ISO to ./assets/ (required before running the viewer)
+# Usage: just extract path/to/game.iso
+extract ISO:
+    cargo run --bin sylpheed-cli -- extract {{ISO}} ./assets/
+    @echo "Extraction complete. Run: just run"
+
+# List files in an ISO
+# Usage: just list path/to/game.iso
+list ISO:
+    cargo run --bin sylpheed-cli -- list {{ISO}}
+
+# Sniff file formats in ./assets/
+sniff:
+    cargo run --bin sylpheed-cli -- sniff ./assets/
+
+# Sniff but only show unknown formats (focus RE effort)
+sniff-unknown:
+    cargo run --bin sylpheed-cli -- sniff ./assets/ --unknown-only
+
+# ── Testing ────────────────────────────────────────────────────────────────────
+
+# Run all tests
+test:
+    cargo test --workspace
+
+# Run tests including ISO integration tests (requires SYLPHEED_ISO env var)
+test-integration:
+    SYLPHEED_ISO=./game.iso cargo test --workspace -- --include-ignored
+
+# ── Code quality ──────────────────────────────────────────────────────────────
+
+# Format all code
+fmt:
+    cargo fmt --all
+
+# Lint
+lint:
+    cargo clippy --workspace -- -D warnings
+
+# Check everything compiles (faster than full build)
+check:
+    cargo check --workspace
+    cargo check --workspace --target wasm32-unknown-unknown
+
+# ── All platforms CI check ────────────────────────────────────────────────────
+
+# Full CI: format check + lint + test + WASM compile check
+ci:
+    cargo fmt --all -- --check
+    cargo clippy --workspace -- -D warnings
+    cargo test --workspace
+    cargo check --target wasm32-unknown-unknown -p sylpheed-viewer
+    @echo "All CI checks passed!"