fix(prompt-input): Adjust image preview hover state and alignment in input head

[chaxus]

Description

This PR improves the prompt-input component's image preview with three key fixes:

Changes

1. Fixed hover cursor - Added cursor-pointer for better interactivity feedback
2. Unified alignment - Made all image previews left-aligned (was inconsistent before)
3. Mobile improvements - Fixed cutoff issues and added proper spacing on small screens

Visual Changes

Desktop Before	Desktop After
Inconsistent alignment & layout jumps	Consistent left alignment & stable layout

Mobile Before	Mobile After
Content cut off, no padding	Proper truncation with spacing

Thanks to the code reviewers! Looking forward to making ai-elements even better.

[vercel]

@chaxus is attempting to deploy a commit to the Vercel Team on Vercel.

A member of the Team first needs to authorize it.

[haydenbleasel]

On a roll @chaxus! Thanks 🚢