feat: add OKX DEX integration with action provider and chatbot example

[Julian-dev28]

Description

This PR implements the OKX DEX integration for AgentKit, enabling AI agents to interact with the OKX DEX API for token swaps and quotes. The implementation includes:

• A new OKXDexActionProvider that supports both quote fetching and token swaps
• Comprehensive schema definitions for quote and swap requests
• Full test coverage for the action provider functionality
• A chatbot example demonstrating the OKX DEX integration
• Updated dependencies and documentation

The integration currently supports Solana (chainId: "501") with infrastructure in place to support additional networks in the future.

Tests

you'll need the following API keys:

• OpenAI API Key
• OKX API Credentials

Once you have them, rename the .env-local file to .env and make sure you set the API keys to their corresponding environment variables:

• "OPENAI_API_KEY" (required)
• "SOLANA_PRIVATE_KEY" (required)
• "SOLANA_RPC_URL" (required)
• "OKX_API_KEY" (required)
• "OKX_SECRET_KEY" (required)
• "OKX_API_PASSPHRASE" (required)
• "OKX_PROJECT_ID" (required)
• "NETWORK_ID" (optional)
• CDP_API_KEY_NAME=[optional. If you'd like to use the CDP API, for example to faucet funds, set this to the name of the CDP API key]
• CDP_API_KEY_PRIVATE_KEY=[optional. If you'd like to use the CDP API, for example to faucet funds, set this to the private key of the CDP API key]

Chatbot: typescript/examples/langchain-okx-chatbot/chatbot.ts
Network: Solana
Setup: Connected to OKX DEX API

Prompt: Swap 0.01 SOL to USDC with 0.5% slippage

-------------------
-------------------
Here are the details for swapping 0.01 SOL to USDC:

- **Exchange Rate**: 1 SOL = 144.93 USDC
- **Expected Output**: 1.449458 USDC
- **Estimated Gas Fee**: 
  - In SOL: 0.000242 SOL
  - In USD: approximately $0.035
- **Price Impact**: -0.03%
  
The swap will be executed through the SolFi protocol, which has a trade fee of approximately 0.000725 SOL.

Do you confirm the swap of 0.01 SOL to 1.449458 USDC?
-------------------

Prompt: yes

-------------------
Got blockhash: 72NS6GU4pqvxWo3w6Gjvnja2HUaVi574PWK5pmNo4xrp
Signing and sending transaction
Transaction sent, track it here: https://web3.okx.com/explorer/solana/tx/2NaCKPTvT5NA5mFu3U1NJmmfQttN4n2PachV5pZz3c8AbJfx9E9VYNZz34F92bxPyG4vcgKwYzhRrUNEZTBiZs8T

could not confirm transaction status using 'processed' blocks, trying one more time using 'confirmed'  blocks...

✅ Swap executed successfully!
🔍 Track transaction: https://web3.okx.com/explorer/solana/tx/2NaCKPTvT5NA5mFu3U1NJmmfQttN4n2PachV5pZz3c8AbJfx9E9VYNZz34F92bxPyG4vcgKwYzhRrUNEZTBiZs8T
-------------------
The swap has been executed successfully! You have swapped 0.01 SOL to approximately 1.449458 USDC.

🔍 You can track the transaction [here](https://web3.okx.com/explorer/solana/tx/2NaCKPTvT5NA5mFu3U1NJmmfQttN4n2PachV5pZz3c8AbJfx9E9VYNZz34F92bxPyG4vcgKwYzhRrUNEZTBiZs8T). 

If you need any further assistance, feel free to ask!
-------------------

Checklist

• Added documentation to all relevant README.md files
  • Added comprehensive README.md in the langchain-okx-chatbot directory
• Added a changelog entry
  • Added changeset for the OKX DEX integration feature

The implementation follows the TypeScript development guidelines and includes:

• Proper error handling and validation
• Type safety with Zod schemas
• Comprehensive test coverage
• Clear documentation and examples
• Secure API key management

Would you like me to help you with anything else in the PR template?

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

[Julian-dev28]

@cb-heimdall hey how's it going? can you please review when you get a chance?