[BUG] Detect fixterm representations or Detect KKP

Environment

• Platform (select one):

unknown - im reporting this on behalf of a ghostty user

• Terminal: Ghostty

Bug Description

claude code does not recognize fixterm key encodings and spits the fixterm encoding into the input box
this is very unintuitve for users

Steps to Reproduce

Use ghostty and use a keybind with a modifier so it will have a fixterm representation (ghostty uses fixterm by default users have to override the keybind manually)
shift + enter to do a newline in the prompt is a easy way to achieve this

Expected Behavior

newline in prompt

Actual Behavior

fixterm encoding is thrown into input box

Additional Context

https://www.leonerd.org.uk/hacks/fixterms/

Kitty keyboard protocol support would also solve this problem
https://sw.kovidgoyal.net/kitty/keyboard-protocol/