fix: changeColorMap example

[bionoone]

Context

example is broken:
https://www.cornerstonejs.org/live-examples/changecolormap

this example demonstrate issue reported in #826 & #2384

depending on color map, there is an opacity "jump" between 99% and 100%

Changes & Results

Testing

Checklist

PR

• My Pull Request title is descriptive, accurate and follows the
  semantic-release format and guidelines.

Code

• My code has been well-documented (function documentation, inline comments,
  etc.)

Public Documentation Updates

• The documentation page has been updated as necessary for any public API
  additions or removals.

Tested Environment

• [] "OS:
• [] "Node version:
• [] "Browser:

Summary by CodeRabbit

• New Features
  • Updated the fusion viewport example to apply a PET color map to the PT volume.
  • CT and PT volumes are now loaded and displayed together for fused visualization.
  • Rendering is triggered after both volumes are configured, resulting in a smoother, single-step fused scene.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: ebe5f00f-2b2b-4605-8bb6-e3638ea02c55

📥 Commits

Reviewing files that changed from the base of the PR and between 60b63eb and 849e7ae.

📒 Files selected for processing (1)

• packages/tools/examples/changeColormap/index.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• packages/tools/examples/changeColormap/index.ts

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📝 Walkthrough

Walkthrough

The colormap example now waits for the PT volume to load, configures CT and PT together with modality-specific transfer functions, enables fusion, and renders the combined viewport.

Changes

Fused volume colormap setup

Layer / File(s)	Summary
Configure fused CT and PT rendering packages/tools/examples/changeColormap/index.ts	The example types the viewport, defers setup until the PT volume is loading, applies CT and PET transfer functions to their respective actors, enables fusion, and renders.

Estimated code review effort: 2 (Simple) | ~10 minutes

Sequence Diagram(s)

sequenceDiagram
  participant run
  participant CTVolume
  participant PTVolume
  participant VolumeViewport
  run->>CTVolume: create CT volume
  run->>PTVolume: start load
  run->>VolumeViewport: setVolumes with CT and PT actors
  VolumeViewport->>VolumeViewport: apply CT and PET transfer functions
  run->>VolumeViewport: enable fusion and render

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	Context is filled, but Changes & Results, Testing, and Tested Environment are left blank or unchecked.	Add a short change summary, before/after results, concrete test steps, and complete OS/Node/browser details.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise, semantic-release style, and matches the change to the changeColormap example.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

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• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
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Inline comments:
In `@packages/tools/examples/changeColormap/index.ts`:
- Around line 204-215: Update the viewport setup flow around viewport.setVolumes
to await its asynchronous completion before setting fused and calling
renderingEngine.render(), ensuring rendering occurs only after both volume
actors are configured.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 69e4feef-5bf6-421b-9d73-80dcbda3f012

📥 Commits

Reviewing files that changed from the base of the PR and between aaf6d3b and 60b63eb.

📒 Files selected for processing (1)

• packages/tools/examples/changeColormap/index.ts