Adds sdfgi_enabled and a ReflectionProbe to all three arenas' Environment
setup so surfaces get real bounce lighting/reflections instead of flat
ambient. Converts arena_boundary.tscn's shared glass field material from
unshaded to a shaded, rim-lit material so it reads as glass (dim face-on,
highlighted at grazing angles) rather than a flat tinted overlay.
Enable glow/bloom, color adjustments, and MSAA+FXAA across all three
arenas so emissive ship/station accents actually bleed light and edges
read cleanly. Expose the player-facing knobs (anti-aliasing mode, glow
intensity, brightness) through a new Settings screen off the main menu,
persisted via a VideoSettings autoload that scales each arena's own
tuned Environment values on load rather than overwriting them.
Josh Creek