Optimize distant factory rendering in v0.40

[NellInc]

Summary

• preserve every authored factory machine body while culling only distant spouting, flow effects, and conveyor detail beyond 200 metres
• add a 190 metre hysteresis return threshold so the unified factory never chatters between detail states
• make static exterior batching deterministic by ordering compatible candidates before bounded startup slicing
• document the measured 11.0 percent water-view draw-call reduction without changing the locked v0.40 version

Verification

• npm run typecheck
• npm run lint
• npm run format:check
• npm test (95 files, 993 tests)
• npm run build (3,588 modules)
• npm run validate:assets
• npm run validate:depth
• npm run validate:shaders
• npm run validate:bundle
• npm run validate:uncrewed
• npm audit --audit-level=high
• npx impeccable detect src
• npm run test:e2e (2 passed)
• release matrix and staged routes validated for v0.40, genuine v0.30, v0.20, and v0.10
• non-art runtime: overview 78.0 FPS, 15.0 ms p95, 1,232 calls; water 71.8 FPS, 15.8 ms p95, 1,269 calls; world continuous and vehicle motion valid
• final overview and water frames visually inspected

Contracts

• version remains 0.40
• no humans, personnel models, host voices, or personnel design studies
• unified inside and outside world remains mounted
• authored town, farm, water, castle, mountains, yards, vehicles, tanks, and factory walls/windows remain present