f271f9d9d8
Adds `for i in start..end` (exclusive) and `for i in start..=end` (inclusive) range loop syntax. Existing `for item in list` iteration is preserved; the parser branches on DotDot/DotDotEq presence after the start expression. Lexer adds DotDot and DotDotEq tokens with longer-match-first priority. Codegen emits a C `for` loop with the loop variable scoped to the statement; inclusive uses `<=`, exclusive `<`.