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

app/api/test/add-cash/route.ts

@@ -0,0 +1,58 @@
+import { getGameDb, persist } from '@/lib/db/client';
+import * as schema from '@/lib/db/schema';
+import { getStateSnapshot } from '@/lib/game/state';
+import { tickNow } from '@/lib/sim/engine';
+
+// TEST-ONLY hook (v0.31.0, ISS-055) — grants cash so the e2e suite can afford a second
+// plane (ATR €200k vs the €20k starting balance). Disabled unless FLIGHT_TEST_HOOKS=1
+// (set in docker-compose.yml for the e2e instance only); every other deployment 404s here.
+// Sibling of /api/test/create-package — same gate, same conventions.
+//
+// POST /api/test/add-cash
+//   body { amount?: number } — a positive finite number when provided; defaults to €1M.
+//   Adds to account.cash (rounded to cents) and returns the full state snapshot.
+
+const DEFAULT_AMOUNT = 1_000_000;
+
+export async function POST(req: Request) {
+  if (process.env.FLIGHT_TEST_HOOKS !== '1') {
+    return Response.json({ error: 'test hooks disabled' }, { status: 404 });
+  }
+
+  let body: unknown = {};
+  try {
+    const text = await req.text();
+    body = text ? JSON.parse(text) : {};
+  } catch {
+    return Response.json({ error: 'invalid JSON body' }, { status: 400 });
+  }
+  if (typeof body !== 'object' || body === null || Array.isArray(body)) {
+    return Response.json({ error: 'body must be a JSON object' }, { status: 400 });
+  }
+  const input = body as Record<string, unknown>;
+  for (const key of Object.keys(input)) {
+    if (key !== 'amount') {
+      return Response.json({ error: `unknown field "${key}"` }, { status: 400 });
+    }
+  }
+  let amount = DEFAULT_AMOUNT;
+  if (input.amount !== undefined) {
+    if (typeof input.amount !== 'number' || !Number.isFinite(input.amount) || input.amount <= 0) {
+      return Response.json({ error: 'amount must be a positive finite number' }, { status: 400 });
+    }
+    amount = input.amount;
+  }
+
+  try {
+    const inst = await getGameDb();
+    await tickNow(); // clock is current before the snapshot we return (same as siblings)
+    const account = (await inst.db.select().from(schema.account))[0];
+    if (!account) throw new Error('account row missing');
+    await inst.db.update(schema.account).set({ cash: Math.round((account.cash + amount) * 100) / 100 });
+    await persist(inst);
+    return Response.json(await getStateSnapshot());
+  } catch (err) {
+    console.error('test hook failed', err);
+    return Response.json({ error: 'test hook failed' }, { status: 500 });
+  }
+}