feat: Add SPL-Governance Treasury Operations

[Rudrakc]

This PR adds SPL Governance program support to the Solana Agent Kit, enabling programmatic DAO treasury monitoring and governance management.

Features Added:

1. Monitor Treasury Balances:

   • Fetch SOL and SPL token balances for governance treasuries.
   • Integrated as monitorTreasuryBalances in SolanaAgentKit.

2. Propose Transactions:

   • Added proposeTransaction for creating governance proposals.

3. Execute Approved Actions:

   • Added executeApprovedTreasuryActions for executing transactions from proposals.

4. LangChain Tools:

   • Integrated tools for all new functionalities.

Files Added/Modified:

• Added functions to SolanaAgentKit (monitorTreasuryBalances, proposeTransaction, executeApprovedTreasuryActions).
• Created corresponding tools in langchain/index.ts.

How It Works:

1. Monitor Treasury Balances:

• Fetches all treasuries for a governance account.
• Retrieves SOL and SPL token balances for each treasury and structures them into a user-friendly format.

2. Propose Transactions:

• Creates a governance proposal with multiple configurable parameters (e.g., proposal name, options, vote type).
• Supports additional metadata like description links.

3. Execute Treasury Actions:

• Executes transactions tied to approved governance proposals.
• Handles execution via SPL Governance’s withExecuteTransaction helper.

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Linked Issues:

Closes #166

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This pull request was created for https://app.gib.work/bounties/9e595117-5d86-42a4-b695-35ead834a4af in an attempt to solve a bounty #166 . Payment for the bounty is immediately sent to the contributor after merge.