Update PLAN.md progress for Phase 9a

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

Author: pirapira

PLAN.md

@@ -780,7 +780,7 @@ For non-deterministic tests, structural equivalence is checked.
 | 8b | Pydantic: validators, serializers, core_schema | Done (field_validator, model_validator before/after, field_serializer, model_serializer, pydantic_core.core_schema module, evalCoreSchema engine, validator inheritance) |
 | 8c | Pydantic: advanced features for leanSpec | Done (extra="forbid" enforcement, alias_generator/to_camel, populate_by_name, model_dump by_alias, ConfigDict MRO inheritance, __get_pydantic_core_schema__ hook, validate_default/arbitrary_types_allowed parsing) |
 | 8d-e | Pydantic: remaining advanced features | Not started |
-| 9a | leanSpec: types | In progress (built-in type subclassing: synthetic classObj for int/bytes, wrappedValue on InstanceData, super().__new__/dunder dispatch, custom exception hierarchy, @override decorator, kwargs forwarding in instance/super method dispatch, bytes dunder dispatch engine, bytes multiplication, bytes(instance) wrappedValue extraction, bytearray builtin, isinstance with tuple of builtins, pow(b,e,None), BaseUint encode/decode round-trip, BaseBytes with length validation, hex/bin/oct on int subclass instances, range/divmod with instances, list indexing/slicing with instance indices, repr/str via Python-defined dunders, bytes.__radd__/comparison dunders, sorted() on bytes subclass instances, Boolean type pattern, in-place operator immutability, reverse operator TypeError dispatch, BytesIO seek+read round-trip, wrappedValue unwrap in comparison ops) |
+| 9a | leanSpec: types | In progress (built-in type subclassing: synthetic classObj for int/bytes, wrappedValue on InstanceData, super().__new__/dunder dispatch, custom exception hierarchy, @override decorator, kwargs forwarding in instance/super method dispatch, bytes dunder dispatch engine, bytes multiplication, bytes(instance) wrappedValue extraction, bytearray builtin, isinstance with tuple of builtins, pow(b,e,None), BaseUint encode/decode round-trip, BaseBytes with length validation, hex/bin/oct on int subclass instances, range/divmod with instances, list indexing/slicing with instance indices, repr/str via Python-defined dunders, bytes.__radd__/comparison dunders, sorted() on bytes subclass instances, Boolean type pattern, in-place operator immutability, reverse operator TypeError dispatch, BytesIO seek+read round-trip, wrappedValue unwrap in comparison ops, **f-string lexer/parser/evaluator with !r/!s/!a conversion**, type() returns classObj for builtins (enables type(x).__name__), BytesIO.write() accepts bytes subclass instances, comprehensive end-to-end tests: SSZType+BaseUint+Uint64 chain, BaseBytes+Bytes32 chain, Boolean+SSZType chain) |
 | 9b | leanSpec: SSZ merkleization | Not started |
 | 9c | leanSpec: consensus containers | Not started |
 | 9d | leanSpec: state transition | Not started |