richat: upgrade to agave 4.0

[fanatid]

Summary

• Upgrade the workspace from Agave/Solana v3.1 to Agave v4.0.0-rc.0 dependencies.
• Raise the Rust toolchain to 1.93.1 for Agave v4.0 compatibility.
• Bump the Richat packages for the breaking upgrade:
  • richat v11.0.0
  • richat-cli v10.0.0
  • richat-client, richat-filter, richat-plugin-agave, richat-proto, and richat-shared v9.0.0
• Update yellowstone-grpc-proto to 12.3.0.
• Update the changelog release entry for the v4 upgrade.

Upgrade Details

• Refresh workspace dependencies for Agave v4 / Solana v4 crates, while keeping v3 aliases where compatibility paths still need them.
• Add local proto conversion helpers for Agave v4 transaction, account, and status types.
• Update filter/message handling for the new transaction-with-metadata shape.
• Update the Agave plugin protobuf encoding paths and benchmark fixtures for the new APIs.
• Update Richat pubsub, storage replay, channel handling, client, CLI, shared config, and QUIC transport code for the new dependency surface.

Breaking Changes

• This is the Agave v4.0 upgrade and is versioned as a breaking Richat release.
• Consumers should use the new package versions listed above together; mixed v8/v9 client, proto, plugin, filter, and shared packages are not expected to be compatible with this branch.
• Building this branch requires the updated Rust toolchain from rust-toolchain.toml.

Verification

• cargo check -p richat