[Optimization] Optimize DOM in tempo.js

[AnvitaPrasad]

Issue: #4461

DOM Optimization in tempo.js widget

Optimized the tempo.js widget to improve performance by:

• Caching canvas contexts during initialization instead of getting them repeatedly in the draw loop
• Creating a style template object for efficient application to multiple canvases
• Caching frequently accessed properties (blockList, logo) to reduce property lookups
• Simplifying conditional logic using ternary operators for cleaner, faster code
• Reusing current time values instead of creating multiple Date objects
• Extracting canvas click handler to a separate method for better organization

changes improve rendering efficiency, especially during animation loops that run at 5ms intervals

[github-actions]

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