Add heat_haze effect — Canvas2D localized heat-shimmer with manifest, docs & tests

[smcga]

Motivation

• Provide a lightweight, Canvas2D-first localized refractive “heat haze” effect that can be used as a layer or base scene and behaves organically with upward drift and micro-turbulence.
• Keep performance friendly on mobile by avoiding full per-pixel getImageData work and reusing offscreen buffers.
• Expose the effect in the existing registry/debug/docs system so it is selectable and documented like other effects.

Description

• Implemented the effect in src/renderer/effects/heatHaze.ts as HeatHazeEffect, using an offscreen canvas and strip-based horizontal displacement driven by layered seeded value-noise, sinusoidal shimmer, and upward advection; a subtle vertical offset and small second-pass softening are included (blurHint).
• Added deterministic noise helpers noise1d and valueNoise1d, and a region-weighting helper getRegionWeight to support region = bottom | band | full with centerY, height, and feather controls.
• Registered the effect via src/renderer/effects/manifest/heat_haze.manifest.ts and added the manifest into the generated registry list (src/renderer/effects/manifest/generated.ts) so it appears in the UI/debug dropdowns.
• Updated the README effect catalog and regenerated docs/effects.md so the effect is documented and the docs generator can parse its parameters (scripts/generateEffectsDocs.ts).
• Added unit tests src/renderer/effects/heatHaze.test.ts for helper determinism and region weighting, and adjusted src/timeline/releaseTimeline.test.ts optional list to include heat_haze so registry coverage tests remain valid.
• Key param set (defaults included): intensity, speed, scale, drift, region, centerY, height, feather, shimmer, blurHint, tint, audioReactive, beatBoost, bassInfluence, seed.

Testing

• Regenerated effect docs with npm run docs:effects and verified via npm run docs:check; docs generation succeeded and docs check passed.
• Ran targeted unit tests with npx vitest run src/renderer/effects/heatHaze.test.ts src/timeline/releaseTimeline.test.ts; both test files passed.
• Ran full test suite via npm test; all project tests passed except an existing external integration test api/kv.integration.test.ts which failed due to network/Upstash connectivity (ENETUNREACH) in the current environment and is unrelated to the effect code.
• Manual smoke notes: effect uses cached offscreen canvas and will fall back to a simple warm background if canvas creation fails (sensible standalone appearance).

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Codex Task

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Project	Deployment	Actions	Updated (UTC)
codexperimental	Ready	Preview, Comment	Apr 4, 2026 2:14am