[BUG] OpenAI Compatible provider using "user" role when not streaming

[whitfin]

Problem (one or two sentences)

We hit an issue with our OpenAI compatible API because when "Enable Streaming" is not checked, the system prompt is provided with a "user" role: https://github.com/RooCodeInc/Roo-Code/blob/main/src/api/providers/openai.ts#L222-L225

I'm happy to file the PR for this, but as I'm not fully familiar with why this was done I'm filing it as a bug with hopes of clarification.

Context (who is affected and when)

This happens when using OpenAI Compatible providers, when a user switches between streaming and non-streamed responses.

Reproduction steps

1. Any Roo environment using "OpenAI Compatible" provider
2. Create a request with streaming enabled
3. Create a request with streaming disabled

Expected result

Role shows as "system" for both requests

Actual result

Role shows "user" for request with streaming disabled

Variations tried (optional)

No response

App Version

3.28.5

API Provider (optional)

OpenAI Compatible

Model Used (optional)

No response

Roo Code Task Links (optional)

No response

Relevant logs or errors (optional)

[roomote]

I'm exploring a potential fix for this issue where the system prompt is incorrectly using 'user' role instead of 'system' role when streaming is disabled in the OpenAI Compatible provider. I'll investigate the code and open a PR to share progress.

[roomote]

Opened a PR with my attempt at addressing this issue: #8216

The fix ensures that the system prompt consistently uses the 'system' role regardless of whether streaming is enabled or disabled. All tests are passing and CI checks have completed successfully. Feedback welcome!

[hannesrudolph]

@whitfin go ahead with a PR. Not sure what the roomote did so check that first.

[whitfin]

@hannesrudolph the roomote PR seems reasonable to me!