Web IDE Visual Polish 26.01

What does this MR do?

• Color changed for line numbers
• Open Folder Icon
• Monospaced Font for branch names and commit messages
• Fixed the Add Dropdown so it is not hidden

Why was this MR needed?

To make the Web IDE prettier.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?