lexer.s turns cached source lines into tokens with stable kinds and error
codes (tokens.inc): 32 keywords, identifiers folded across both PETSCII
letter ranges, decimal/hex/binary numbers to 65535, strings and character
literals with escapes, all operators, and comments. An error reports its
exact column, then the rest of the line is skipped.

An independent host reference lexer and the C128 lexer in x128 both
reproduce the reviewed golden token files: 10 fixtures, 1,119 tokens,
including one fixture per error kind. A case-folding mutation is caught.

Spec 2.2 now lists <= and >=, matching section 8. D119 (proposed): the \n
and \r escapes both produce $0D. The monitor helper now reads RAM bank 0,
because BASIC ROM hides $4000+ after a program returns.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>