Add shadowVolumes Canvas effect with docs, manifest, and tests

[smcga]

Motivation

• Provide a single new Canvas2D effect shadowVolumes that evokes classic hard-edged shadow-volume silhouettes using deterministic projected geometry and audio-reactive motion.
• Keep scope minimal and compatible with the existing effect system (params, manifest, debug controls, era tuning, and mobile-safe framing).
• Ensure the effect is deterministic for a fixed seed and can be automated from the timeline/editor.

Description

• Implemented the ShadowVolumesEffect in src/renderer/effects/shadowVolumes.ts with projection helpers, seeded occluder generation, shadow-polygon construction, era tweaks, and audio reactivity.
• Added debug/manifest registration src/renderer/effects/manifest/shadow_volumes.manifest.ts and included it in the generated manifest list (src/renderer/effects/manifest/generated.ts).
• Added unit tests src/renderer/effects/shadowVolumes.test.ts covering param resolution/clamping, deterministic occluder generation, projection stability, and finite shadow polygon output.
• Updated documentation and catalog: appended effect entry to README.md and regenerated docs/effects.md so the effect appears in the registry/docs and the debug dropdowns.
• Placed a small, non-invasive example layer entry in public/timeline.release.json so release coverage tests include the new effect.

Testing

• Ran the new helper/unit tests with npm run test -- src/renderer/effects/shadowVolumes.test.ts and they passed.
• Regenerated docs with npm run docs:effects and verified docs consistency via npm run docs:check, both succeeded.
• Ran the focused timeline and catalog tests (src/timeline/releaseTimeline.test.ts, src/renderer/effects/effectCatalogDocs.test.ts) and they passed after adding a small layer reference in the release timeline.
• Ran the full test suite with npm run test; all project tests passed except an external integration test api/kv.integration.test.ts which failed due to network DB reachability in this environment (ENETUNREACH) and is unrelated to the effect changes.

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Project	Deployment	Actions	Updated (UTC)
codexperimental	Ready	Preview, Comment	Apr 4, 2026 2:13am