feat(aggregation-layers): port HexagonLayer to WebGPU

[ibgreen-openai]

Goal

Port HexagonLayer's cell renderer to WebGPU as a small, low-risk extraction from #10450, and expose the existing website example through the device tabs.

Changes

• Added WGSL vertex/fragment shader support for HexagonCellLayer.
• Added WGSL declarations for the hexagon uniforms and color-range texture bindings.
• Kept the WebGL shader path aligned with master: the new WGSL source is only returned when the active device is WebGPU; the existing GLSL vertex shader and module setup remain unchanged for WebGL.
• Passed the selected device into the 3D heatmap example and enabled its WebGL2/WebGPU tabs.

Website examples

Layer / example	WebGPU aggregation	WebGPU render path	Status
HexagonLayer / 3D heatmap	Existing CPU fallback when WebGLAggregator is unavailable	HexagonCellLayer WGSL shader	✅ Works

The aggregation behavior is unchanged: WebGPU already selects the existing CPU aggregator because WebGLAggregator.isSupported(device) is false. This PR only ports the cell rendering path.

Validation

• yarn build
• yarn lint (passes; repository's existing warnings remain)
• yarn test-headless test/modules/aggregation-layers/hexagon-layer.spec.ts
• yarn test-website
• Manual website check: selected the WebGPU tab on /examples/hexagon-layer; the example rendered and the browser console had no errors.

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: ccbeb67275

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[ibgreen-openai]

Review follow-up: the reviewer thread is addressed and resolved in e7aefda. Local build, lint, and focused HexagonLayer tests passed. GitHub CI is green, and the PR is approved and mergeable; safe to merge from review and CI standpoint.