Allow proper types for agent props

[stof]

Describe the bug
The generic types for Agent enforces Record<string, unknown> as bound for Props. This Record type requires subtypes to define an index signature for type string, which prevents using interfaces with well-defined properties.

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
While the type could still default to Record<string, unknown>, it should allow using proper interfaces that have no index signature.

Screenshots

This is the error reported by Typescript on a getAgentsByName call passing { props: config } as third argument:

Version:
0.17.3

Additional context

[mattzcarey]

@agent-think repro this pls