#2589 (PR #2500): a @protocol declaration (labeled <Name>) is excluded from
the receiver-type index, so it no longer collides with a same-named class.
#2590 (PR #2501): a category/class-extension interface is keyed off the
base stem and folds into the base class instead of minting a duplicate
node.
#2591 (fresh): @property and ivar declarations are captured into a
per-class field-type table, and a message send to a self.field / _ivar
receiver resolves through it (bare field name only, so Foo.shared cannot
fabricate to a FooShared class). All hold the single-definition guard and
emit INFERRED.
Adapts PRs #2500/#2501 (thanks @xiongjianxu); #2591 fresh.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
