v1.15.0 — 88 checks

18 new checks (CH071-CH088), bringing the total from 70 to 88.

Same discipline as every prior batch: every 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. Two candidate checks (enum member aliasing, bare-except swallowing asyncio.CancelledError) were built, corpus-scanned, and rejected outright — both independently rediscovered false-positive patterns this project had already rejected once before, using different real-world evidence. See docs/FINDINGS.md for the full precision notes.

New checks catch, among others:

• A decorator's wrapper missing @functools.wraps — real hits across 17 projects
• @abstractmethod on a class with no ABCMeta to enforce it — real hits across 17 more
• A duplicate method definition silently shadowing the first
• Dataclass/NamedTuple field ordering (kw_only, init=False, ClassVar, the KW_ONLY sentinel, all handled)
• __slots__ conflicting with a class-level variable
• Python 2 special methods (__nonzero__, __unicode__, ...) Python 3 silently never calls
• A defaultdict subscript read as an if condition inserting the key as a side effect
• json.dumps() on a raw datetime
• A weakref to an object with no other reference
• A regex flag landing in re.sub's count slot instead of flags

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