fix(ui): canvas sliders misc

[psychedelicious]

Summary

• Set an empty title to prevent browsers from showing "Please match the requested format." when hovering the number input
• Fix issue w/ z-index that prevented the popover button from being clicked while the input was focused

Related Issues / Discussions

https://discord.com/channels/1020123559063990373/1149513625321603162/1293369992288538644

QA Instructions

n/a

Merge Plan

n/a

Checklist

• [x] The PR has a short but descriptive title, suitable for a changelog
• [ ] Tests added / updated (if applicable)
• [ ] Documentation added / updated (if applicable)