SL-1/SL-4: dark-frontier visual cohesion pass (camera, grade, bullseye)

Research-grounded transform of the base arena from a bright meadow into a dark 'Aether Siege Outpost' reading as a concentric bullseye (Core -> Ore ring -> dark perimeter). Camera (Game.unity): pitch 45->58, FOV 55->44, dist 13->17, lead 1->0.5, follow 8->6, targetH 1.3 (telephoto so Core + arena read together, near-iso enemy spacing). Lighting: sun dimmed+cooled 1.6->0.9, ambient 1.0->0.62 dark-cool, fog Linear 18->42 dark; WorldAtmosphere base darkened. Post-FX (PostFX_Daylight): ACES kept, bloom gated (thr 1.0->1.2 + clamp 10), exposure/contrast up, saturation +6->0, added ShadowsMidtonesHighlights cool-shadow/warm-highlight split, vignette 0.15->0.32. Ground re-tinted dark teal-grey; ~390 meadow-cheer objects cut. Core staged as hero (crystal 14m->4.6m cyan glow + cyan beacon light). Ore ring pulled into the arena (23.5-27m -> 6-11.5m, count 10->12) and recoloured AMBER (new Mat_OreNode_Amber, emissive, no atlas bleed).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Assets/_Project/Subscenes/Gameplay.unity

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