v1.16.0 — 100 checks

12 new checks (CH089-CH100), bringing the total to 100.

Same discipline as every prior batch: each check verified empirically before implementation, corpus-scanned against ~30 real open-source frameworks, and narrowed against real false positives rather than shipped on first pass.

CH091 (hash-eq-field-mismatch) was the deepest precision chase this project has done — seven distinct, legitimate ways for __hash__ and __eq__ to reference "the same field" without looking alike syntactically (a method call or @property standing in for a field, multi-field equality via a tuple or a wrapping call instead of named pairs, blanket equality via __dict__ or dataclasses.fields() reflection, and a property wrapping a differently-named private attribute). One genuine bug survived all seven rounds: semantic-kernel's ChatHistorySummarizationReducer hashes two fields its __eq__ never compares.

CH096 (post-init-on-non-dataclass) went from 615 false positives to 1 after finding the same "something else calls __post_init__" convention independently reinvented twice (vllm's own @config decorator, transformers' PreTrainedConfig.__init__ hook).

New checks also catch:

• str/bytes mixed in the same .join()
• __exit__ unconditionally suppressing every exception
• Path.write_text()/write_bytes() given the wrong type
• asyncio.to_thread() given an async function (never runs its body)
• The same keyword passed both directly and via **-dict-unpack
• A lambda target on a spawn/forkserver multiprocessing context
• raise NotImplemented instead of NotImplementedError
• Two __slots__-declaring bases colliding
• str.maketrans() with mismatched-length arguments
• __iter__ returning self with no __next__

Zero runtime dependencies, verified via a fresh pip install into a clean venv.