Paho Rust v2 Coming Soon! - 100% Rust

[fpagliughi]

Since it's creation about 9 years ago, the Paho Rust MQTT library has been a wrapper around the Paho C library. That got us to a full-featured library in the shortest amount of time, but from the start, the intention was to get a stable API, and then rewrite the internals in 100% Rust. But neither the free time nor the corporate funding could ever be found to do this.

About a year ago the decision was made that this full Rust version should happen before the library hit a decade old! Nights and weekends have been given over to the effort. With a little AI assist, it is coming together.

The plan is currently as follows:

1. Create one last major update to the C-wrapper version and promote it to v1.0. This v1.x line will continue to be maintained for a while, primarily to track any new features and performance enhancements added to the C library, but not much new coding will be done on the Rust side.
2. Simultaneously release the new 100% Rust version as v2.0.

This is planned to all happen by the end of this year, 2026.