Variables and path parameters are not considered for SSE

### Expected Behavior

When using variables in headers or path variables in an SSE request, these are not evaluated before sending a request.
I expect that they are evaluated before the request is made.

This has been happening for quite some time and was never properly fixed. Unfortunately this forces me to put actual tokens has hardcoded values in my headers.

See https://github.com/Kong/insomnia/issues/7709

### Actual Behavior

things like `{{_.token}}` are sent verbatim to the server. Same for path variables such as `:caseId`.

### Reproduction Steps

_No response_

### Is there an existing issue for this?

- [x] I have searched the [issue tracker](https://www.github.com/Kong/insomnia/issues) for this problem.

### Which sync method do you use?

- [ ] Git sync.
- [ ] Insomnia Cloud sync.
- [ ] Local only

### Additional Information

_No response_

### Insomnia Version

10.3.0

### What operating system are you using?

macOS

### Operating System Version

15.2

### Installation method

downloaded directly

### Last Known Working Insomnia version

_No response_

Start by tracing the SSE request handling and compare it with the evaluation path used for other request types. Reproduce the issue with a header containing {{_.token}} and a path containing :caseId; done means both variables are evaluated before the SSE request is sent.

Written by the indexing model from the issue text.