Add game mode categories, character creation, on-foot ship/hub mode, RAM currency, and in-ship navigation

Bundles several sessions' worth of previously uncommitted work: map
categories with Domination/Conquest/King of the Hill mode stubs and a
server-list mode filter; a procedurally-drawn character-creation screen
replacing the old callsign-only PROFILE overlay; the on-foot groundwork
(walkable station hub, ship interior, character controller) plus the RAM
currency backend; and today's addition, an in-ship Helldivers-2-style
navigation table that QUICK PLAY's queue/connect flow and the Belters/
Military hub travel now live behind, with hub-and-ship return paths and a
context-aware pause menu usable both in-match and inside the ship.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

matchmaking-api/app/routers/stats.py

@@ -22,4 +22,5 @@ async def get_stats(callsign: str, db: AsyncSession = Depends(get_db)) -> Player
         kills=player.kills,
         deaths=player.deaths,
         hours_played=player.hours_played,
+        ram_kb=player.ram_kb,
     )