feat: various improvement for claude configuration

[varex83]

This PR addresses the problem that we had very big (300+ lines) AGENTS file, which could become problematic for AI to follow (i.e. to broad concepts, missing general information and a lot of specific knowledge (like type mappings))

This PR introduces:

• Check charon folder hook - on each session start it identifies charon folder in typical paths ("charon", "../charon", "../../charon", to be extended). If not found - prompt AI to clone (should it done automatically as well?)
• Charon Guide - contains basic overview of the Go implementation, the official Charon's CLAUDE.md was used as a base.
• check-formatting hook basically formats file after each change
• Also decomposed AGENTS.md into three: AGENTS.md, rust-style and porting skills.

Things that are good: it now follows the instructions much better, spending less time locating the repository and understanding the pluto codebase

Things that are bad: it now follows the instructions very precisely, and we need to play with prompts more. For example, when asking to implement dkg/sync package, it successfully and quickly navigated charon, gathered context and made a plan, but it copied the structure of the Go implementation 1-to-1, despite we have different approach to P2P.

Specifically to p2p - I will create a separate skill (for now it's empty), explaining the structural differences between rust and go.