Arch/modularize artwork asset registry

[vanshika2720]

PR Description: Modularize artwork.js into a Managed AssetRegistry

Overview

This PR refactors the monolithic js/artwork.js file to eliminate global namespace pollution and provide a modern, centralized API for visual asset management. By moving from ad-hoc regex replacements to a structured AssetRegistry, we improve code maintainability and solve the long-standing "architectural bottleneck" associated with SVG handling in Music Blocks.

Key Changes

• Implemented AssetRegistry: A central repository in js/artwork.js for all SVG assets and visual constants.
• Implemented getSVG(iconName, options): A new, consistent API for retrieving and dynamically styling SVGs (supporting fillColor, strokeColor, and arbitrary placeholders).
• Migrated Major Consumers: Successfully updated turtles.js, activity.js, EnsembleBlocks.js, turtle-painter.js, trash.js, themebox.js, and palette.js to use the new API.
• Dependency Cleanup: Heavily reduced the global variable dependencies in multiple core files.
• Expanded Testing: Added comprehensive unit tests for the new registry and API in js/__tests__/artwork.test.js.
• Lint Fixes: Resolved existing ESLint warnings in touched files to ensure compatibility with strict pre-commit hooks.

How to Test

1. Run npm test js/__tests__/artwork.test.js to verify the new API.
2. Run npm test js/blocks/__tests__/EnsembleBlocks.test.js to ensure block rendering logic is preserved.
3. Open Music Blocks in a browser and verify that turtle shells, palette icons, and the trash basket render correctly with their expected colors.

Goal

Reduce the memory footprint of the global namespace and modernize visual asset management for Music Blocks v4.

• Performance

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Failed Tests:

palette.test.js
trash.test.js

[vanshika2720]

still working/testing

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Failed Tests:

palette.test.js
trash.test.js

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Failed Tests:

artwork_integration.test.js
themebox.test.js

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Failed Tests:

artwork_integration.test.js

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Failed Tests:

toolbar.test.js

[github-actions]

❌ Some Jest tests failed. Please check the logs and fix the issues before merging.

Failed Tests:

toolbar.test.js