Add CLAUDE.md, switch to static adapter for nginx deployment

- CLAUDE.md: build commands, architecture overview, coordinate systems,
  WASM rebuild instructions for future development sessions
- Switch from adapter-auto to adapter-static with SPA fallback
  (outputs to build/ directory for nginx serving)
- Install @sveltejs/adapter-static dependency

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -0,0 +1,53 @@
+# Mass Driver — Interplanetary Relay Network Simulator
+
+## Project Structure
+Rust workspace + SvelteKit frontend compiled to WASM.
+
+```
+crates/
+  orbital-mechanics/  — Pure Rust: Kepler solver, Lambert solver, orbit propagation, Lagrange points
+  mass-driver-core/   — Station placement, transfer matrix computation, Dijkstra routing
+  mass-driver-wasm/   — Thin wasm-bindgen wrapper exposing core to JS
+  mass-driver-backend/ — Axum cache server (Postgres)
+frontend/             — SvelteKit + Threlte (Three.js) + Canvas2D
+```
+
+## Build Commands
+
+```bash
+# Rust tests
+cargo test
+
+# Build WASM (required before frontend)
+cd crates/mass-driver-wasm && wasm-pack build --target web --release
+
+# Frontend dev server
+cd frontend && npm run dev -- --port 5173
+
+# Frontend production build
+cd frontend && npx vite build
+
+# Backend (needs DATABASE_URL env var)
+cargo run -p mass-driver-backend
+```
+
+## Key Architecture
+- Orbital mechanics runs in WASM (Rust compiled to WebAssembly)
+- Frontend loads WASM on mount, calls it every animation frame for body positions
+- Route computation: Lambert solver → transfer matrix → time-expanded graph → Dijkstra
+- 2D view: Canvas2D with manual drawing. 3D view: Threlte (Svelte Three.js wrapper)
+- Positions in AU (ecliptic coords), converted to screen pixels (2D) or Three.js units (3D)
+- Ecliptic→Three.js mapping: X→X, Y→-Z, Z→Y (Three.js is Y-up)
+
+## WASM Rebuild
+After changing any Rust code in orbital-mechanics, mass-driver-core, or mass-driver-wasm:
+```bash
+cd crates/mass-driver-wasm && wasm-pack build --target web --release
+```
+The frontend links to the WASM pkg via `file:../crates/mass-driver-wasm/pkg` in package.json.
+
+## Coordinate Systems
+- Rust returns positions in AU, ecliptic frame (X=vernal equinox, Y=90° in ecliptic, Z=north pole)
+- Lambert solver works in km (positions × AU_KM constant)
+- 2D canvas: AU mapped to pixels via zoom factor
+- 3D scene: 1 AU = 50 Three.js units, Y-up convention