Restructure into pnpm monorepo with game shell, docs, and SpacetimeDB backend

- Restructure flat static prototype into pnpm workspace monorepo
- apps/game: playable shell with R3F 3D scene, HUD, SpacetimeDB connection
- apps/docs: design docs and prototypes
- apps/site: landing page
- packages/ui: shared Button and Panel primitives
- services/spacetimedb: backend module (9 tables, 11 reducers)
- Archive legacy static files to archive/legacy-static/
- Game loop: connect, undock, target, approach, dock, mine, sell
- Add pnpm-workspace.yaml, tsconfig.base.json, spacetime.json

apps/game/src/ui/CargoPanel.tsx

@@ -0,0 +1,35 @@
+import { Panel } from "@void-nav/ui";
+import type { CargoItem, Ship } from "../module_bindings/types";
+
+export function CargoPanel({ cargo, ship }: { cargo: CargoItem[]; ship?: Ship }) {
+  const used = cargo.reduce((total, item) => total + item.quantity, 0n);
+  const capacity = ship?.cargoCapacity ?? 0n;
+
+  return (
+    <Panel className="p-4">
+      <div className="flex items-baseline justify-between gap-3">
+        <p className="m-0 font-mono text-xs uppercase tracking-[0.1em] text-muted">Cargo</p>
+        <span className="font-mono text-xs text-fg-dim">
+          {used.toString()} / {capacity.toString()}
+        </span>
+      </div>
+      <div className="mt-3 grid gap-2">
+        {cargo.length > 0 ? (
+          cargo.map((item) => (
+            <div key={String(item.cargoItemId)} className="rounded-md border border-border bg-bg-subtle px-3 py-2">
+              <div className="flex items-center justify-between gap-3 text-sm">
+                <span className="font-semibold text-fg-bright">{item.itemName}</span>
+                <span className="font-mono text-xs text-cyan">{item.quantity.toString()}</span>
+              </div>
+              <div className="mt-1 font-mono text-xs uppercase tracking-[0.08em] text-muted">
+                {item.category} / {item.unitPrice.toString()} ISK
+              </div>
+            </div>
+          ))
+        ) : (
+          <p className="m-0 rounded-md border border-border bg-bg-subtle p-3 text-sm text-fg-dim">Cargo hold empty.</p>
+        )}
+      </div>
+    </Panel>
+  );
+}