feat(tui): query Kitty keyboard protocol support before enabling

- Query terminal with CSI ? u before enabling Kitty protocol
- Only enable protocol if terminal responds (100ms timeout)
- Mode-aware key parsing: when Kitty active, interpret legacy
  sequences as custom terminal mappings (e.g. \x1b\r = shift+enter)
- Add Terminal Setup section to README with Ghostty/wezterm config

fixes #439

packages/tui/src/index.ts

@@ -30,7 +30,7 @@ export {
 	setEditorKeybindings,
 } from "./keybindings.js";
 // Keyboard input handling
-export { Key, type KeyId, matchesKey, parseKey } from "./keys.js";
+export { isKittyProtocolActive, Key, type KeyId, matchesKey, parseKey, setKittyProtocolActive } from "./keys.js";
 // Terminal interface and implementations
 export { ProcessTerminal, type Terminal } from "./terminal.js";
 // Terminal image support