Add unit tests for temperament.js to improve coverage

[stutijain2006]

This PR adds comprehensive unit tests for the temperament.js file to improve its test coverage and reliability.

What was added:
Added test cases for core methods including:

• playNote()
• playAll()
• edit()
• equalEdit()
• ratioEdit()
• arbitraryEdit()
• octaveSpaceEdit()
• _refreshInnerWheel()
• _graphOfNotes()
• _save()
• checkTemperament()

Covered multiple execution branches such as:

• Equal temperament path
• Ratio temperament path
• Default frequency branch
• Reverse playback logic
• Stop playback logic
• Octave space adjustments

Added appropriate mocking for:

• docById
• document.createElement
• wheelnav
• Singer
• Browser-specific globals
• Canvas rendering context (getContext)
• External helper functions like rationalToFraction, getOctaveRatio, etc.

Impact-

• temperament.js coverage increased from 0% to ~33%.
• Improved confidence in playback, editing, and saving logic.
• Reduced risk of regressions in core temperament functionality.

[github-actions]

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

[github-actions]

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

[mahesh-09-12]

hey @stutijain2006, nice coverage addition here, good to see multiple branches of playNote, playAll, and edit modes being exercised. The constructor and save paths are also covered, which helps protect core flows. One small suggestion is some tests override internal methods like checkTemperament or simplify behavior, it would be stronger to assert observable behavior instead of patching logic where possible, to avoid masking regressions. Overall, this is a solid step toward stabilizing the widget logic.