Review panel updates

[arvsrn]

Issue for this PR

N/A

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

• Updated tabs to use dnd-kit to match the rest of the app
• Updated tab styles, and file sidebar styles
• Restructured file sidebar so it doesn’t remount on tab changes
• Added back the open in button

How did you verify your code works?

• Ran the app locally and verified the updated UI manually
• Ran type checks locally (bun turbo typecheck)
• Ran v1 locally to confirm no changes affect v1

Screenshots / recordings

N/A

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR

If you do not follow this template your PR will be automatically rejected.