Re-verified the POC against the post-refactor alknet-core (BidiStreamSource
trait, ADR-070): all 28 tests still pass, clippy fully clean (the upstream
Connection::close unused-arg warnings are gone). Updated the POC's handler
tests to use AuthContext::anonymous(alpn) (REQ-CORE-03), removing the
four-None-field literal that recurred across echo_handler and tunnel_handler.
Issues #1 (BidiStreamSource), #2 (Connection::close unused args), and #3
(AuthContext verbosity) in the POC summary are now marked RESOLVED with
pointers to ADR-070 / commit 60cce22. Issues #4-#7 (channels-side: zero-length
sentinel on shutdown, dynamic mux registration, demux EOF teardown, two-pump
shutdown-on-completion) remain for Phase 1. POC scope note added: the POC
correctly keeps Connection::from_stream (yield-once) — building
ChannelBidiStreamSource is Phase 1's job, now unblocked by the trait.