Bump vendor/nwaku to 4a3db364 (feat/logos-testnetv02-mix) so
mountKademlia skips switch.mount when client=true. Enable clientMode
and disable XPR publish for fleet mix discovery (lookup-only). Link
mix librln in make tests so smoke_test links on Darwin.
Add rust-bundle, a single staticlib crate that depends on both libchat
and rln as rlibs. This ensures rustc links Rust std exactly once,
eliminating duplicate symbol errors on all platforms. Nim targets link
against liblogos_chat_bundle.a; Nix uses a bundleDrv instead of
separate libchat and rln derivations.
Reference: https://doc.rust-lang.org/reference/linkage.html#mixed-rust-and-foreign-codebases