fix(web): fetch all unit runtimes on page load

Root cause: state.runtimes was empty after refresh because the engine
only pushes UnitRuntimeChanged on state transitions — if the engine
is mid-wait-phase, no push occurs and badges show OFFLINE.

Fix: add GET /api/unit/runtimes batch endpoint (returns all known
runtimes as { unit_id: UnitRuntime }) and call it in parallel with
the unit list fetch inside loadUnits(), so runtime badges are correct
immediately after page load.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/control/runtime.rs

@@ -81,6 +81,10 @@ impl ControlRuntimeStore {
             .clone()
     }
 
+    pub async fn get_all(&self) -> HashMap<Uuid, UnitRuntime> {
+        self.inner.read().await.clone()
+    }
+
     /// Wake the engine task for a unit (e.g., when auto_enabled or fault_locked changes).
     pub async fn notify_unit(&self, unit_id: Uuid) {
         if let Some(n) = self.notifiers.read().await.get(&unit_id) {

src/handler/control.rs

@@ -509,3 +509,11 @@ pub async fn get_unit_runtime(
     let runtime = state.control_runtime.get_or_init(unit_id).await;
     Ok(Json(runtime))
 }
+
+/// Returns all known runtimes as { unit_id: UnitRuntime }.
+/// Used by the frontend on page load to populate initial state.
+pub async fn get_all_unit_runtimes(
+    State(state): State<AppState>,
+) -> impl IntoResponse {
+    Json(state.control_runtime.get_all().await)
+}

src/main.rs

@@ -209,6 +209,10 @@ fn build_router(state: AppState) -> Router {
             "/api/unit",
             get(handler::control::get_unit_list).post(handler::control::create_unit),
         )
+        .route(
+            "/api/unit/runtimes",
+            get(handler::control::get_all_unit_runtimes),
+        )
         .route(
             "/api/unit/{unit_id}",
             get(handler::control::get_unit)

web/js/units.js

@@ -180,7 +180,10 @@ export function renderUnits() {
 }
 
 export async function loadUnits() {
-  const response = await apiFetch("/api/unit?page=1&page_size=-1");
+  const [response, runtimes] = await Promise.all([
+    apiFetch("/api/unit?page=1&page_size=-1"),
+    apiFetch("/api/unit/runtimes").catch(() => ({})),
+  ]);
   state.units = response.data || [];
   state.unitMap = new Map(state.units.map((unit) => [unit.id, unit]));
 
@@ -188,6 +191,10 @@ export async function loadUnits() {
     state.selectedUnitId = null;
   }
 
+  for (const [unitId, runtime] of Object.entries(runtimes)) {
+    state.runtimes.set(unitId, runtime);
+  }
+
   renderUnits();
   renderUnitOptions(dom.equipmentUnitId?.value || "", dom.equipmentUnitId);
   renderUnitOptions(dom.equipmentBatchUnitId?.value || "", dom.equipmentBatchUnitId);