3718bf0380
El SDK CI - dev / build-and-test (pull_request) Failing after 3m44s
runtime/channel.el has always called __channel_new/__channel_send/ __channel_recv/__channel_try_recv/__channel_close, but these were only ever implemented in the pre-restructure lang/el-compiler/runtime/el_runtime.c. When the canonical runtime was consolidated onto the release copy (lang/runtime/el_runtime.c) and el_seed.c became the sole C dependency, the channel implementation was never carried forward — __mutex_new made the move, __channel_* did not. Any El program using Go-style channels currently fails to link on dev. Ported the working buffered-MPMC-channel implementation (mutex+condvar+ circular buffer, bounded and unbounded modes) from the old el_runtime.c verbatim, adapted only to el_seed.c's arena API (seed_arena_track in place of el_arena_track). Declared in el_seed.h alongside the existing mutex primitives.