chat_channel.c: new chat_core_create_channel_auto(name) — generates
X25519/Ed25519 keys, random channel_id, Ed25519 signature, creates channel.
chat_core_create_channel_auto_trampoline for gui_bridge_post_uasync_fn.
mainwindow.cpp: onCreateGroupRequested() reduced from 100 to 15 lines.
Removed openssl/evp.h and openssl/rand.h includes from UI code.