🚴 Fiber Dev Log 07 🚴 Init Compatibility Check, Multi-Part Payments Support, and Audit Fixes

We recently got the code audit report—been heads-down fixing issues and leveling up Fiber.

A couple of updates from this sprint:

- FeatureVector support is in. Nodes now exchange Init messages and check for feature compatibility before opening channels—this helps make connections safer and more reliable.

- Basic Multi-Part Payments (MPP) support has landed. It now covers path-finding, HTLC hold settlement, and a refactored attempt mechanism.

And we're continuing work on more advanced MPP features.

Full log: https://github.com/nervosnetwork/fiber/discussions/735