Shared parser: extend PyExprMode suppression to tkShl/tkXor

Filed under Track A (shared parser.inc) by the N-lane agent, self-resolved per the combined-track rule (sole A holder confirmed this session).

ParseTerm consumed tkShl and ParseSimpleExpr consumed tkXor at Pascal precedence even in PyExprMode, so NilPy's 1 << 2 + 3 parsed as (1 shl 2) + 3 = 7 instead of Python's 1 << (2+3) = 32, and ^ never reached the NilPy bitwise chain. Same mechanism as the existing and/or suppression: gate both on not PyExprMode. Pascal paths unchanged (PyExprMode is only set while parsing .npy expressions).

Resolved with [[feature-nilpy-operators]].