Signature Help not available

### What should be done?

Signature Help (parameter info popup) works in Zed but doesn't appear in VS Code. The extension may need to register signature help provider with the right trigger characters.

### How should it be done?

The LSP server already handles signature help, verify the request is being sent from VS Code and the response is rendered.

### When is this task done?

Signature help popups appear in VS Code when typing trigger characters.

### Additional context

_No response_