Complete Phase 3b: boundMethod refactor, exceptions, int/bytes/tuple methods

Replace fragile string-encoded method dispatch with clean boundMethod Value
variant, fixing a bug where string methods failed on strings containing
underscores. Add typed exception handling (raise/except with type matching
and hierarchy), int methods (bit_length, to_bytes, from_bytes), bytes methods
(hex, fromhex, decode), tuple methods (count, index), map/filter builtins,
hasattr/getattr, set operations (difference, intersection, symmetric_difference,
issubset, issuperset, isdisjoint), dict merge operator, and bytes concatenation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pirapira