Initial project setup: Rust/WASM solar system simulator with SvelteKit frontend

- Rust workspace with 4 crates: orbital-mechanics, mass-driver-core, mass-driver-wasm, mass-driver-backend
- Keplerian orbital mechanics engine with JPL elements for 14 bodies (Sun, 8 planets, Pluto, Ceres, Europa, Titan, Ganymede)
- Kepler equation solver and orbital position computation compiled to WASM
- SvelteKit frontend with Tailwind CSS, Canvas2D renderer showing animated solar system
- Orbit ellipses, planet dots with labels, Sun glow, grid, scale bar, pan/zoom controls
- Time controls (play/pause, 5 speed levels, date picker) driving live simulation
- 2D/3D view toggle (3D placeholder for Threlte integration)

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

crates/mass-driver-core/src/lib.rs

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+pub mod station;
+pub mod route;

crates/mass-driver-core/src/route.rs

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+use serde::{Deserialize, Serialize};
+
+/// A single leg of a route between two stations.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RouteLeg {
+    pub from_station: usize,
+    pub to_station: usize,
+    /// Departure week index (0 = first week of simulation)
+    pub departure_week: u32,
+    /// Arrival week index
+    pub arrival_week: u32,
+    /// Weeks spent waiting at departure station before this leg
+    pub wait_weeks: u32,
+}
+
+/// The result of a route computation.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RouteResult {
+    pub legs: Vec<RouteLeg>,
+    /// Total elapsed time in weeks from departure to final arrival
+    pub total_time_weeks: u32,
+    /// The week index when the package departs the origin
+    pub departure_week: u32,
+}

crates/mass-driver-core/src/station.rs

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+use serde::{Deserialize, Serialize};
+
+/// How a station is placed in the solar system.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum StationPlacement {
+    /// Station in heliocentric orbit
+    SolarOrbit {
+        a: f64,       // Semi-major axis (AU)
+        e: f64,       // Eccentricity
+        i: f64,       // Inclination (degrees)
+        omega: f64,   // Longitude of ascending node (degrees)
+        w: f64,       // Argument of perihelion (degrees)
+        m0: f64,      // Mean anomaly at epoch (degrees)
+    },
+    /// Station in orbit around a planet
+    PlanetaryOrbit {
+        parent_body_id: usize,
+        altitude_km: f64,
+        inclination: f64,
+    },
+    /// Station at a Lagrange point
+    LagrangePoint {
+        primary_body_id: usize,   // e.g., Sun
+        secondary_body_id: usize, // e.g., Earth
+        point: LagrangePointId,
+    },
+}
+
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq)]
+pub enum LagrangePointId {
+    L1,
+    L2,
+    L3,
+    L4,
+    L5,
+}
+
+/// A mass driver relay station.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Station {
+    pub id: usize,
+    pub name: String,
+    pub placement: StationPlacement,
+}