Boxed records (C4): resolve each record's copy/free function from the GIR
copy-function/free-function attribute, else its own ref/copy and unref/free
method, and render init(retaining:) plus an isolated deinit. The deinit is
isolated because the package's default MainActor isolation makes accessing the
non-Sendable pointer from a nonisolated deinit a hard error. The registry uses
the same resolution so transfer=none returns copy instead of adopting a
borrowed pointer. This supersedes the earlier deferral: the hypothesised
OpaquePointer/Sendable barriers either did not hold or were solvable.
Interfaces (C5): plan each interface method through planMethod and render it as
a protocol requirement (no body); the conforming class supplies the C call.
Brendan Szymanski
164f8b7b9a