refactor: complete Canvas interface ownership

[jderochervlk]

Tracking issue: #342

Stack context

Part 27 of the Option 5 folder-feature stack.

• Previous: refactor: establish Navigator folder feature #336
• Next: complete Device interface ownership

Review this PR as the incremental diff against #336.

Summary

• move ImageData and VideoColorSpace from the legacy DOM folder into src/canvas
• expose both existing flat interface modules through WebAPI.Canvas
• leave the Canvas feature dependency closure unchanged

Why this follows the Canvas PR

The initial Canvas layer focused on the existing Canvas source folder. These two value interfaces were still published from the broad DOM folder even though their types and consumers belong to Canvas. Keeping this as a two-file follow-up makes that ownership correction explicit.

Temporary state

• ScreenOrientation remains the last clear non-Window interface in the legacy DOM folder and moves in the next Device follow-up
• the remaining legacy DOM source entry is removed by the subsequent Window layer
• final feature-graph guardrails and helper cleanup remain deferred until the stack is complete

Review focus

• ownership of the two value interfaces
• unchanged flat public module paths and Canvas closure

Verification

• node_modules/.bin/rescript clean
• node_modules/.bin/rescript build --prod --features DOM,Event,DOMPlatform,Animation,CSSOM,Geometry,DOMNodes,File,HTML,Media,SVG,Canvas
• npm run build
• npm test
• npm run format:check
• git diff --check

[jderochervlk]

@codex

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. More of your lovely PRs please.

Reviewed commit: ab8b5e46df

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