Updated xmtp chatbot to use CDP v2 wallets and new xmtp/agent-sdk

[phdargen]

Description

This PR updates the xmtp chatbot example:

• Replaces xmtp/node-sdk with new xmtp/agents-sdk
• Replaces legacy CDP wallet provider with new CDP v2 wallet provider
• Adds new /fund <amountInEth> command that trigger tx request to send ETH from connected user browser wallet to agent wallet, needs to be signed by user

Tests

Chatbot: typescript/examples/langchain-xmtp-chatbot/chatbot.ts
Network: Base Sepolia
Setup: XMTP keys generated with pnpm run gen:keys

Initializing Agent on XMTP...
Agent initialized on dev network
Agent address: 0xf0191e26a7ae7f011b1c5fbd32d83f572e26bcea
Send a message on http://xmtp.chat/dm/0xf0191e26a7ae7f011b1c5fbd32d83f572e26bcea?env=dev
Listening for messages...

Received message from 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e: Gm, request some usdc
Creating new agent for user: 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e, wallet data: Not found
Creating new memory store for user: 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e
Wallet data saved for user 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e
Sent response to 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e: I have successfully requested USDC from the faucet. Transaction hash: **0x15753617f091f456322438e30f49205575300e333c5ad7512bb58058d697fcfe**

Received message from 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e: request eth
Using existing agent for user: 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e

Received message from 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e: check usdc balance
Using existing agent for user: 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e
Sent response to 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e: Your USDC balance is **1 USDC**. 

Received message from 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e: send all usdc to 0xf2d4580adfe8e012f5550322706d62df11fdbe21
Using existing agent for user: 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e
Sent response to 21a4826bb001d31fcc282d63103e66f981b5f4d257f7978777e454c59c0ce27e: The transfer of **1 USDC** to **0xf2d4580adfe8e012f5550322706d62df11fdbe21** has been successfully completed. Transaction hash: **0xce49ac37c21dc4ac0f7e5e84161d710f85c2425311826fbeaeb17ab292e97c88**. 

Checklist

A couple of things to include in your PR for completeness:

• Added documentation to all relevant README.md files
• Added a changelog entry

[cb-heimdall]

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