[Feature Request] Add theme/background color customization per terminal instance

Bug Description
I'd like to be able to change claude's background color or theme per terminal so I can more quickly visually distinguish between different claude panes in a multi instance session

Environment Info

• Platform: linux
• Terminal: vscode
• Version: 2.1.117
• Feedback ID: 3bf74c84-129e-4145-a0f2-356410774ed1

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /home/prmichaelsen/.local/share/claude/versions/2.1.117 (expected in multi-process scenarios)\n    at Dn$ (/$bunfs/root/src/entrypoints/cli.js:2756:2177)\n    at tq6 (/$bunfs/root/src/entrypoints/cli.js:2756:1257)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-04-22T22:45:28.222Z"}]