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>

crates/sylpheed-viewer/src/lib.rs

@@ -0,0 +1,95 @@
+//! # sylpheed-viewer
+//!
+//! Bevy-based asset viewer for Project Sylpheed: Arc of Deception.
+//!
+//! This crate serves as both:
+//! - A **native binary** (via `main.rs`) — full desktop viewer
+//! - A **WASM library** (this file) — browser viewer at `index.html`
+//!
+//! ## Architecture
+//! - `sylpheed_formats` handles all binary parsing — no Bevy dependency
+//! - This crate is the thin Bevy integration layer on top
+//! - `asset_loader` bridges the two: wraps parsers as `AssetLoader` impls
+//!
+//! ## WASM notes
+//! On the web, local file access is unavailable. Assets must be
+//! pre-extracted and served over HTTP. XISO reading is native-only.
+
+use bevy::prelude::*;
+use bevy_egui::EguiPlugin;
+
+pub mod asset_loader;
+pub mod camera;
+pub mod ui;
+
+// ── Application state ────────────────────────────────────────────────────────
+
+/// Global viewer state, shared across all UI and rendering systems.
+#[derive(Resource)]
+pub struct ViewerState {
+    /// Which type of asset is currently being browsed / previewed.
+    pub current_mode: ViewMode,
+    /// Whether to render meshes in wireframe mode (toggle with F2).
+    pub wireframe: bool,
+}
+
+impl Default for ViewerState {
+    fn default() -> Self {
+        Self {
+            current_mode: ViewMode::Textures,
+            wireframe: false,
+        }
+    }
+}
+
+/// The active view / asset type being inspected.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub enum ViewMode {
+    /// XPR2 texture preview (Milestone 1).
+    #[default]
+    Textures,
+    /// 3D mesh viewer (Milestone 2+).
+    Mesh,
+    /// Audio waveform / playback (Milestone 2+).
+    Audio,
+}
+
+// ── App builder ──────────────────────────────────────────────────────────────
+
+/// Build and run the viewer application.
+///
+/// Called from `main.rs` on native and from `wasm_bindgen` init on the web.
+pub fn run() {
+    let mut app = App::new();
+
+    app.add_plugins(
+        DefaultPlugins.set(WindowPlugin {
+            primary_window: Some(Window {
+                title: "Project Sylpheed: Arc of Deception — Asset Viewer".into(),
+                resolution: (1280.0, 720.0).into(),
+                ..default()
+            }),
+            ..default()
+        }),
+    );
+
+    app.add_plugins(EguiPlugin);
+    app.add_plugins(asset_loader::SylpheedAssetPlugin);
+    app.add_plugins(camera::OrbitCameraPlugin);
+    app.add_plugins(ui::ViewerUiPlugin);
+
+    app.init_resource::<ViewerState>();
+
+    // Minimal 3D scene: a directional light so meshes are visible
+    app.add_systems(Startup, setup_scene);
+
+    app.run();
+}
+
+fn setup_scene(mut commands: Commands) {
+    commands.spawn(DirectionalLight {
+        illuminance: 10_000.0,
+        shadows_enabled: true,
+        ..default()
+    });
+}