feat: step-based missions around park machines with 3D objective arrow

Phase 5 of turning the game into the company landing page.

- Replace purchase-only missions with a data-driven list of short step
  chains (goto, locate on map, inspect, order, buy, buy at N places)
  in src/game/missions, with pure progress logic on the game state.
- Six missions, most about machines installed in Park Mellat; add two
  sites there (lake and sports fields) and record the product model
  installed at every site.
- Inspecting a machine opens a machine card with the installed model,
  specs, price, an order request and sales contact.
- The objective chip shows the current step; the missions sheet lists
  missions with the current one's steps ticked; a brand-coloured arrow
  hovers over the target machine.
- Rewards and banners per finished mission, the next step is spoken.
- Tests for mission data, step logic, text and the machine card.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/pages/game/GameDialogs.jsx

@@ -7,6 +7,7 @@ import { InstallDialog } from './InstallDialog.jsx';
 import { UpdateNotice } from './UpdateNotice.jsx';
 import { EndDialog } from './EndDialog.jsx';
 import { GpsFallbackDialog } from './GpsFallbackDialog.jsx';
+import { MachineCard } from './MachineCard.jsx';
 /** Composes independently managed game dialogs. */
 export function GameDialogs(props) {
   return (
@@ -20,6 +21,7 @@ export function GameDialogs(props) {
       <UpdateNotice {...props} />
       <EndDialog {...props} />
       <GpsFallbackDialog {...props} />
+      <MachineCard {...props} />
     </>
   );
 }