xterm.js sends plain \r for Enter regardless of modifiers. Intercept
modified Enter in the custom key handler so it routes through CSI u
encoding (Kitty keyboard protocol), which Claude Code uses for
Shift+Enter newlines.
On non-Mac platforms, Ctrl+C now copies selected text to clipboard
(falling through to SIGINT when nothing is selected) and Ctrl+V
pastes from clipboard into the terminal.
On non-Mac platforms, let xterm.js ClipboardAddon handle Ctrl+C (copy
when text is selected) and Ctrl+V (paste) instead of sending control
codes to the PTY.
Closes#175
Client-side xterm.js was generating Device Attributes responses via
onData, which fed back to the PTY as visible text. Register CSI handlers
to consume query responses on the client and respond to DA1 on the server.
Mohamed Boudra