[Feature Request] Support multiple file drag-and-drop upload

Bug Description
ファイルを複数同時にドラッグドロップで入れらるようにして欲しい。

Environment Info

• Platform: darwin
• Terminal: cursor
• Version: 2.1.12
• Feedback ID: b6ae7054-9503-42d8-8ed0-7bd2e1c3dc2b

Errors

[{"error":"Error: NON-FATAL: Lock acquisition failed for /Users/zumzumzum/.local/share/claude/versions/2.1.12 (expected in multi-process scenarios)\n    at HZR (/$bunfs/root/claude:3279:2091)\n    at aYA (/$bunfs/root/claude:3279:1202)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-20T15:05:24.430Z"},{"error":"Error: 1: Command failed with ERR_STREAM_PREMATURE_CLOSE: cursor --force --install-extension anthropic.claude-code\nPremature close \n    at q67 (/$bunfs/root/claude:1043:4019)\n    at async $67 (/$bunfs/root/claude:1043:1623)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-20T15:05:26.572Z"}]