[BUG] studio-showcase: volumetric clouds clip through the skyline, AO streaks on towers, permanently inert health HUD

[Noisemaker111]

Playtest of Games/studio-showcase (engine feature demo — a procedurally-generated skyline, lake, grass fields, pole line, all sourced from editor.scene.json with no hardcoded geometry). Typecheck clean, 10/10 tests pass; boots with no missing-GLB crash. As a showcase, visual polish is the product, and close inspection of the hero frame (shots/studio-showcase-boot.png, captured twice identically) finds render defects:

• The volumetric cloud layer hard-clips through the downtown skyline. A flat blurry white-grey band slices horizontally across several midtown towers at a fixed screen-space height, cutting their upper floors off behind a hard edge — reads as a compositing bug, not atmosphere. world.ts sky.volumetricClouds (height 110, thickness 58). Deterministic (identical in both captures). This is the single most prominent background element, so it undercuts the "showcase" bar. Likely an engine render-order/depth-compositing issue in packages/core post/sky.
• AO streaking on two skyscrapers — thin near-black vertical bars rise out of rooftops mid-facade, disconnected from any modeled geometry. STUDIO_STAGE_POST.ao = { intensity: 2.2, radius: 1.4 } (packages/core/src/render/postProcessing.ts:86) is aggressive enough to streak at building-edge silhouettes rather than read as contact shadow. (Partly could be SwiftShader, but AO intensity is an authored constant worth revisiting.)
• The health HUD is wired but permanently inert. game/entities/players/catalog.ts:14 sets health.max: 100 with no regen/damage config, and game/ui/GameUI.tsx:8-16 HealthPill just reads it — nothing in src ever mutates health (grepped). As a showcase of the HUD building blocks, a static, unreachable "100/100 HP" undersells the primitive.
• One hillside tree renders pale/washed-out vs neighbors — suspected instance of the quaternius-stylized-nature texture-layout bug ([BUG] Committed quaternius-stylized-nature assets store textures under Textures/ but GLBs reference them flat → foliage textures 404 across ~5 games #1338), unconfirmed (RPC hung).

Movement/camera/interact/announce-zone are unverified — the warm-loop capture hung (headless harness flakiness), not a known game defect.

Filed from a full playtest sweep of all 11 Games/* (recon only).

[Noisemaker111]

Claiming the cloud clipping and AO streak items: the cloud proxy dome writes its own depth at the raymarch's first cloud hit so scene geometry occludes it correctly, and the studio stage AO is tuned down. Health HUD and the pale tree are game-side and stay open. Refs #1353.