[JamieW105]

Scene authors could not attach, preview, save or script reusable visual effects. Add 26 typed scene effect kinds, deterministic CPU simulation, effect assets/composites with instance overrides, native editor authoring and live preview, and public lifecycle/event APIs through the existing scripting boundary.

The implementation extends scene snapshots/component serialization, undo transactions, asset sidecars/importers and the retained renderer. It includes batched transparent geometry and textured particles, material/camera modifiers, bounded child spawning, analytical water surfaces, sampled post-processing, 35 editable presets and a runnable gallery with replay controls. Agent object tools and bundled authoring guidance accept validated effect configurations.

Validation:

• Workspace check, strict all-target Clippy and formatting.
• World: 74 unit and 11 integration tests passed (one performance test ignored); engine-play: 112 full-suite tests plus the live saved-gallery replay test passed.
• Editor: 86 application tests passed (one existing browser fixture ignored); 45 model tests passed, including curve dragging and isolated sub-emitter previews.
• All 29 renderer tests on software Vulkan and all 29 on GLES, including real sprite assets, distortion, fog, blend modes and cleanup.
• Library tests: assets 23, project 10, scripting 53 passed.
• Debug CPU simulation/extraction smoke: 10,000 particles over 120 frames in 1.552 seconds; no GPU timing claim.
• Generated gallery imports/reloads, covers all 26 types and renders from its serialized scene; preview is in the example README.

Keep this PR in draft. Full specification acceptance is not established: GPU simulation, true HDR bloom, runtime probe capture, packed decal ORM, through-wall outlines, standalone effect material overrides, advanced fog scattering and temporal/motion-vector effects remain unimplemented and are documented. Browser export was not exercised end to end. The required Windows installer command was attempted but PowerShell is unavailable on this Linux host; no fresh installer was produced.