L2: Implement Solana chain module

[zjwjing]

Description

Implements the Solana chain backend for Arka, supporting SOL transfers, SPL token transfers, and balance queries.

Closes #22

Changes

New Files

• src/chains/solana.rs - Solana chain implementation
• ests/solana_test.rs - Integration tests
• examples/multi_chain_solana.rs - Multi-chain example

Features

SolanaChain

• SOL balance queries
• SPL token balance queries
• SOL transfers
• SPL token transfers
• Account existence checks
• Block height and slot queries

SolanaClient

• High-level wallet operations
• Auto-creates Associated Token Accounts
• Simplified API for agent operations

Constants

• Well-known program IDs (System, Token, Associated Token)
• Chain IDs for mainnet, devnet, testnet

Testing

Tests require solana-test-validator:
�ash solana-test-validator cargo test --test solana_test

Wallet Address

ETH: 0x8971bC40f06e90015C5e92d247c96BfB65C24Cc7

[abhicris]

Welcome to kcolbchain, @zjwjing — glad you're here. 🌱

Here's what happens from this PR:

1. Our automated review looks for obvious issues (tests, secrets, size) within a couple of hours.
2. If it's clean and CI passes, we merge without back-and-forth.
3. If we need changes, we'll leave a specific comment — not a generic nit. Push another commit and we re-review.

While you wait:

• Run the repo's tests locally (see the repo README.md).
• Keep the PR scoped to one concern — bigger PRs land slower.
• Don't commit tokens or .env contents.

What happens after your first merge

• You're listed on https://kcolbchain.com/contributors/ (opt-out anytime via data/contributors-optout.txt).
• At 2+ merged PRs you're a Regular; at 5+ you're a Fellow — Fellows are the pool we invite first for paid research, partner-org gigs, and grant-funded work. Details: https://kcolbchain.com/docs/org-contribution-policy.html
• Looking for what to pick up next? https://kcolbchain.com/invitations/ lists open help-wanted / good-first-issue across every kcolbchain repo.

Thanks for writing the code. We're building this to last.

[abhicris]

🤖 Audit verdict: safe

Solana chain module adds legitimate RPC client functionality with no hardcoded secrets, properly parameterized fund transfers, or malicious payloads.

Audited by the kcolbchain PR pipeline. See pipeline docs.

[zjwjing]

Hi maintainers,

I have completed all the requested changes and the PR is ready for review.

Please let me know if you need any additional modifications.

Thank you!