Two-plane load fix + e2e coverage (ISS-055, v0.31.0)

- LoadControls preselects the first eligible plane so Load is one-click with N planes
- LeftPane queue testids scoped by plane id (queue-leg/cancel/add[-dest]-{plane.id})
  — unscoped ids duplicated in the DOM with two on-board blocks
- new POST /api/test/add-cash hook (FLIGHT_TEST_HOOKS=1, default €1M) so e2e can
  afford a second plane; returns the full state snapshot
- new serial spec e2e/two-planes.spec.ts: load, parallel fly + ISS-057 slow/resume,
  refuel, relocate, per-plane queues with auto-chain, sell (6 tests)
- e2e/queue.spec.ts locators updated to the scoped testids

components/RightPane.tsx

@@ -49,8 +49,9 @@ export function loadEligiblePlanes(state: StateSnapshot, pkg: PackageState): Pla
 // Load controls for one open package: a single Load button when exactly one plane
 // is eligible (it acts on that plane directly), a small plane picker + Load when
 // several are, and a disabled button with the reason otherwise. Each row owns its
-// selection in local state and defaults to the "Select a plane…" placeholder —
-// never preselecting — so rows stay visibly independent (v0.10.1 pattern).
+// selection in local state; ISS-055 (v0.31.0): the multi-plane path PRESELECTS the
+// first eligible plane so Load is one-click out of the box (matching the single-plane
+// UX) while the picker still allows choosing a different plane.
 function LoadControls({
   pkg,
   eligible,
@@ -63,8 +64,9 @@ function LoadControls({
   onLoad: (planeId: string) => void;
 }) {
   const [selectedId, setSelectedId] = useState<string | null>(null);
-  // The user's pick while it stays eligible, else nothing (placeholder).
-  const effective = eligible.find((p) => p.id === selectedId) ?? null;
+  // ISS-055 (v0.31.0): the user's pick while it stays eligible, else the FIRST eligible plane —
+  // Load is enabled and one-click whenever ≥1 plane qualifies; the picker still allows a different pick.
+  const effective = eligible.find((p) => p.id === selectedId) ?? eligible[0] ?? null;
 
   if (eligible.length === 1) {
     return (