Document why supports_statement_cache must be redeclared on the async dialect

The async dialect subclass ostensibly duplicates the base dialect's
supports_statement_cache = True declaration, but the duplication is
actually load-bearing. SQLAlchemy reads this attribute via
``self.__class__.__dict__.get("supports_statement_cache")`` (in
engine/default.py::_supports_statement_cache), which is a single-class
lookup, not an MRO walk. Removing the subclass declaration silently
disables statement caching on the async dialect and emits a runtime
warning on every engine startup. Leave an inline comment pointing at
the SQLAlchemy code path so a future reader doesn't simplify this away.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/sqlalchemydqlite/aio.py

@@ -157,6 +157,13 @@ class DqliteDialect_aio(DqliteDialect):  # noqa: N801
 
     driver = "dqlitedbapi_aio"
     is_async = True
+    # MUST be redeclared here even though the base class already sets it to
+    # True: SQLAlchemy reads this attribute via
+    # ``self.__class__.__dict__.get("supports_statement_cache")`` (see
+    # engine/default.py::_supports_statement_cache), which is a
+    # single-class lookup, not an MRO lookup. If this line is removed,
+    # statement caching is silently disabled on the async dialect and a
+    # warning fires on every engine startup.
     supports_statement_cache = True
 
     @classmethod