Parser parses optional deriving clause; only appended to AST when non-empty.
hk-bind-decls! data arm generates dictShow_Con / dictEq_Con per constructor.
hk-binop == and /= now deep-force both sides (SX dict equality is by
reference — two thunks wrapping the same value compared as not-equal without
this). Three token-type fixes in the deriving parser (lparen/rparen/comma,
not "special").
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
