Fix terminal Ctrl+A/D tab cycling

[parsakhaz]

Summary

• Preserve native Ctrl+A/Ctrl+D behavior for real focused text inputs.
• Exempt xterm.js helper textarea from that input guard so terminal focus can still use Pane tab cycling.

Visual Overview

Before:

flowchart LR
  Key[Ctrl+A / Ctrl+D in terminal] --> Xterm[xterm helper textarea]
  Xterm --> InputGuard[Hotkey input guard]
  InputGuard --> Blocked[Pane tab cycling blocked]

Loading

After:

flowchart LR
  Key[Ctrl+A / Ctrl+D in terminal] --> Xterm[xterm helper textarea]
  Xterm --> Exempt[xterm target exemption]
  Exempt --> Hotkey[Pane hotkey store]
  Hotkey --> Switch[Switch panel tabs]

Loading

Testing

• pnpm run --filter frontend typecheck
• pnpm run --filter frontend lint
• git diff --check
• Pre-commit hook: full workspace typecheck and lint passed

Note: local commands report the existing Node engine warning because this shell uses Node v20.19.3 while the repo requires >=22.14.0.