Flight queue backend: planes hold a queue of upcoming legs, auto-chain on landing (ISS-043 part 1)

- planes.queue TEXT NOT NULL DEFAULT '[]' — ordered JSON array of not-yet-started
  leg ICACs; active leg stays destIcao + departureSimTime. DDL + guarded ALTER
  migration for existing DBs; seed sets queue: [] explicitly.
- deliverPackages() auto-chains on arrival: with a non-empty queue and fuel
  covering the first queued leg (same requiredFuelFor rule as /fly), the plane
  immediately starts that leg from the arrival airport (stays 'flying',
  departureSimTime = arrival instant, queue shortened). Short tank → grounds
  safely with the queue kept intact; empty queue → unchanged grounding. Cargo
  delivery for the reached airport runs first and is unaffected. Ordering kept:
  delivery still runs before tickOnce's pause check, so a chained plane counts
  as still flying — no premature last-plane pause (ISS-041 preserved).
- New endpoints via performAction(): POST /api/planes/{planeId}/queue {destIcao}
  (append; works grounded or flying; 400 bad body/unknown ICAO, 404 unknown
  plane) and POST /api/planes/{planeId}/queue/cancel {index} (remove queued leg
  by index; active in-flight leg never affected; 400 non-integer/out-of-range,
  404 unknown plane). Both return the full state snapshot.
- PlaneState.queue: string[] in /api/state (null/malformed-safe parse helper
  shared with the engine); OpenAPI updated (PlaneState.queue, QueueLegRequest,
  CancelQueuedLegRequest, both paths) and openapi.test.ts expectations extended.
- Tests: auto-chain block in engine.test.ts (chain / short-fuel ground / empty
  queue) + chained-plane-no-pause regression guard; queueLeg/cancelQueuedLeg
  blocks in actions.test.ts; type-compat queue: [] fixtures in deriveEvents,
  right-pane, mapData and seed tests.

v0.25.0 — part 1 (backend) of ISS-043; UI/map rendering lands in a follow-up.

lib/game/state.ts

@@ -24,6 +24,21 @@ export interface PlaneState {
   departureSimTime: number | null;
   lat: number;
   lon: number;
+  // Upcoming legs NOT yet started (v0.25.0, ISS-043) — ordered ICAOs; the active
+  // leg is destIcao. The engine auto-chains queue[0] on landing when fuel covers it.
+  queue: string[];
+}
+
+// Parse the planes.queue JSON column into an ICAO list (v0.25.0). Guards against
+// null/empty/malformed values so a corrupt cell can never break a snapshot or tick.
+export function parseIcaoQueue(raw: string | null): string[] {
+  if (!raw) return [];
+  try {
+    const v: unknown = JSON.parse(raw);
+    return Array.isArray(v) ? v.filter((x): x is string => typeof x === 'string') : [];
+  } catch {
+    return [];
+  }
 }
 
 export interface PackageState {
@@ -108,6 +123,7 @@ export async function getStateSnapshot(): Promise<StateSnapshot> {
         departureSimTime: p.departureSimTime,
         lat: live?.lat ?? p.lat,
         lon: live?.lon ?? p.lon,
+        queue: parseIcaoQueue(p.queue),
       };
     }),
     packages: packageRows.map((p) => ({