Package weight, payload capacity and per-kg payout (ISS-045)

Packages carry a real weightKg (unit weight x count with +/-30% jitter),
plane capacity becomes maxPayloadKg instead of 6 slots, load validation
sums cargo weight against the payload, and the payout gains a per-kg part.
Loadout display shows tonnage; OpenAPI swaps CatalogEntry.capacity for
maxPayloadKg and adds PackageState.weightKg.

components/LeftPane.tsx

@@ -9,7 +9,7 @@ import { formatCash, formatDeadlineRelative, formatFuel, formatSimClock } from '
 import { TIME_SCALES, scaleToSlider, sliderToScale } from '@/lib/timeScale';
 import { useGameAction } from '@/lib/useGameAction';
 import { useSimClock } from '@/lib/useSimClock';
-import { slotsUsedFor } from './RightPane';
+import { cargoWeightFor } from './RightPane';
 import type { HoverTarget } from './hoverTypes';
 
 interface LeftPaneProps {
@@ -39,13 +39,12 @@ function planeLocation(p: PlaneState): string {
   return p.locationName;
 }
 
-// Cargo loadout "n/capacity pkgs" — expired packages still occupy their slot.
+// Cargo loadout "X.Xt / Y.Yt" (v0.27.0) — used/max payload in tonnes, one decimal;
+// expired packages still occupy their payload.
 function loadoutFor(state: StateSnapshot, p: PlaneState): string {
-  const used = state.packages.filter(
-    (pkg) => pkg.planeId === p.id && (pkg.status === 'loaded' || pkg.status === 'expired'),
-  ).length;
-  const capacity = state.catalog.find((e) => e.model === p.model)?.capacity ?? PLANE_TYPES[p.model]?.capacity ?? 0;
-  return `${used}/${capacity} pkgs`;
+  const used = cargoWeightFor(state, p.id);
+  const maxPayloadKg = state.catalog.find((e) => e.model === p.model)?.maxPayloadKg ?? PLANE_TYPES[p.model]?.maxPayloadKg ?? 0;
+  return `${(used / 1000).toFixed(1)}t / ${(maxPayloadKg / 1000).toFixed(1)}t`;
 }
 
 // ISS-001 — an optimistic slider value is cleared exactly when a rendered snapshot CONFIRMS it
@@ -207,7 +206,7 @@ export default function LeftPane({ state, loading, error, onRefresh, applySnapsh
   // ISS-043 (v0.26.0): a plane with queued legs always shows its block too — the queue is the
   // reason it's here even when grounded with nothing on board.
   const onboard = state
-    ? state.planes.filter((p) => p.status === 'flying' || slotsUsedFor(state, p.id) > 0 || (p.queue?.length ?? 0) > 0)
+    ? state.planes.filter((p) => p.status === 'flying' || cargoWeightFor(state, p.id) > 0 || (p.queue?.length ?? 0) > 0)
     : [];
 
   // ISS-023 (v0.21.0): Relocate — any GROUNDED plane can be repositioned to any airport via the