GameSurface Layering

This repo intentionally separates the generic game surface from the current staged mission fixture.

Layer 1: Generic Game Surface

The RG40XXV client in ports/game-surface/ should stay reusable for any 36-tile graph correspondence.

It owns:

• 640x480 rendering, map overlays, unit sprites, and window assets
• cursor movement, unit selection, tile menus, unit menus, pause menu, and exit flow
• generic nested menus for tile, unit, node, output, routing, and review/correction flows
• polling /state and /nodes
• invoking movement/review actions through the HTTP API

It should not hard-code keyboard-mission task meaning into visible UI labels. Mission-specific language should come from the server response and appear only as node names, output summaries, or review text.