[Feature Request] Add Emacs keybinding mode support

Bug Description
We need emacs, mode. Claude can't just have vim mode. This is a serious issue.

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.0.29
• Feedback ID: eb7e931a-bf83-4a47-8e13-20b779526625

Errors

[{"error":"Error: Language not supported while highlighting code, falling back to markdown: \n    at YD (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1175:4413)\n    at file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1175:4141\n    at Array.map (<anonymous>)\n    at MF (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1175:4132)\n    at YTQ (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:1797:6306)\n    at Vw (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:73:19414)\n    at Io (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:75:42806)\n    at T9 (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:75:38347)\n    at zc (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:75:38275)\n    at Lw (file:///opt/homebrew/lib/node_modules/@anthropic-ai/claude-code/cli.js:75:38129)","timestamp":"2025-10-30T03:54:48.615Z"}]