fix: align base url in client if api runs on a different port

[C0ldSmi1e]

Relates to

Risks

Low

Background

What does this PR do?

Currently, the client depends on the api (server) base url, which is hardcoded in client/src/lib/api.ts:

const BASE_URL = "http://localhost:3000";

If we would like to run the server on another port, we can modify the SERVER_PORT in .env, while we still need to update the BASE_URL in the client/src/lib/api.ts.

This PR will align the server port, so that we only need to update the .env if we need to run the server on a different port.

It also ensures the single source of credential.

What kind of change is this?

Improvements

Documentation changes needed?

My changes do not require a change to the project documentation.

Testing

Where should a reviewer start?

Run the project on a different port, and see if the client works as expected.

Detailed testing steps

[github-actions]

Hi @C0ldSmi1e! Welcome to the elizaOS community. Thanks for submitting your first pull request; your efforts are helping us accelerate towards AGI. We'll review it shortly. You are now an elizaOS contributor!