* Move to logos-messaging ffi
Replace waku-bindings crate with direct libwaku FFI via logos-messaging-nim.
The DS layer is now fully synchronous with a dedicated background thread
for the embedded Waku node. Includes discv5 peer discovery, safe FFI
trampoline pattern, and proper resource cleanup via Drop.
* update readme
* fix lint error
* Enhance build configuration and documentation for Waku feature
- Updated `build.rs` to conditionally link to `libwaku` only when the "waku" feature is enabled, improving build flexibility.
- Added a new `waku` feature in `Cargo.toml`, allowing optional dependencies on `base64` and `libc`.
- Enhanced the README to document the new feature flag and its usage, clarifying how to enable Waku transport.
- Updated various modules to reflect the requirement of the `waku` feature for Waku-related implementations, ensuring better clarity in usage.
