Add mass driver station system with Lagrange point placement

- Lagrange point computation (L1-L5) for any Sun-planet pair in Rust
- Station generation: auto-place at Lagrange points by priority (inner → outer planets)
- Station panel UI: count slider (5-50), launch velocity slider (5-100 km/s) with info tooltip
- Blue diamond markers on 2D canvas with labels when zoomed in
- Active station list in sidebar (Earth L1, Mars L2, Jupiter L4, etc.)
- WASM API: generate_stations(), get_station_positions(), get_station_names()
- Station positions update every frame (co-rotating with planets at Lagrange points)

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

crates/mass-driver-wasm/src/api.rs

@@ -1,3 +1,4 @@
+use mass_driver_core::station;
 use orbital_mechanics::bodies;
 use orbital_mechanics::orbits;
 use wasm_bindgen::prelude::*;
@@ -66,3 +67,34 @@ pub fn get_orbit_points(body_id: usize, jd: f64, samples: usize) -> Vec<f64> {
     }
     orbits::orbit_points(&all, body_id, jd, samples)
 }
+
+/// Generate default stations and return their configuration as JSON.
+#[wasm_bindgen]
+pub fn generate_stations(count: usize) -> String {
+    let stations = station::generate_default_stations(count);
+    serde_json::to_string(&stations).unwrap()
+}
+
+/// Get station positions at a given Julian Date.
+/// Takes a JSON config string (from generate_stations) and returns
+/// Float64Array of [x0, y0, z0, x1, y1, z1, ...] in AU.
+#[wasm_bindgen]
+pub fn get_station_positions(stations_json: &str, jd: f64) -> Vec<f64> {
+    let stations: Vec<station::Station> = match serde_json::from_str(stations_json) {
+        Ok(s) => s,
+        Err(_) => return vec![],
+    };
+    let all_bodies = bodies::all_bodies();
+    station::all_station_positions(&stations, &all_bodies, jd)
+}
+
+/// Get station names from a config JSON string.
+#[wasm_bindgen]
+pub fn get_station_names(stations_json: &str) -> String {
+    let stations: Vec<station::Station> = match serde_json::from_str(stations_json) {
+        Ok(s) => s,
+        Err(_) => return "[]".to_string(),
+    };
+    let names: Vec<&str> = stations.iter().map(|s| s.name.as_str()).collect();
+    serde_json::to_string(&names).unwrap()
+}