sc_derive_node_id() hashed the private key, while invite links
(joindialog.cpp) hashed the public key — giving two different
node_ids for the same keypair.
Removed sc_derive_node_id(), kept only sc_derive_node_id_from_pubkey().
All callers updated to use pubkey-based derivation.
- debug_ui.h: remove NDEBUG guard so GUI_ERROR works in Release builds
- invite_link.h/cpp: add error field to InviteData with specific failure reason
- joindialog: show exact decode error in QLabel instead of generic message
- chat_sync: implement invite connect flow (CHANNEL_INFO_REQ/RESP, JOIN, WELCOME)
- topo_node_sqlite: node/address table init and lookup
- utun_node: getInviteAddresses fallback from ETCP sockets
- minor fixes in mainwindow, chat_core, gui_bridge
Evgeny
jeka