Complete Phase 5C: C3 MRO, __new__, attr hooks, class decorators, __slots__, @DataClass

- C3 MRO linearization replacing simple dedup-flattening for correct
  diamond inheritance resolution
- __new__ method support with object.__new__(cls) for custom allocation
- __getattr__ fallback when normal attribute lookup fails
- __setattr__/__delattr__ hooks with object.__setattr__/object.__delattr__
  for direct access bypassing hooks
- __annotations__ dict captured during class body execution
- __dict__, __class__, __name__, __mro__ special attributes on instances/classes
- Class decorator application (@decorator on class definitions)
- __slots__ support restricting instance attributes to declared names
- @DataClass decorator auto-generating __init__, __repr__, __eq__ with
  frozen=True, slots=True, and default value support

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

Author: pirapira