Fix infinite looping for MiMo

[Barragek0]

📝 What does this change?

Adds repetition_penalty: 1.2 to MiMo payloads to fix infinite-thinking-loop observed in MiMo v2.5 / v2.5 Pro.

XiaomiMiMo/MiMo-Code#914 - Important excerpt from the Root Cause Analysis section: NVIDIA community notes that repetition_penalty=1.2 mitigates MiMo "Thought Loop" failure mode

Contrary to most information I found on this issue, it does seem to happen when reasoning is off in MiMo too, it just seems to be less frequent, so I added it for both reasoning on and off.

🧪 How did you test it?

Tested with MiMo v2.5 / v2.5 Pro on High and Off reasoning effort, no longer loops endlessly.

✅ Checklist

• npm run compile passes
• npm run lint passes
• npm test passes (324/324)
• npm run package produces a VSIX
• I tested it works
• I updated docs/CHANGELOG

[ltmoerdani]

Nice one @Barragek0, this is a clean fix and the upstream research checks out.

Verified on my side: checked out the branch, tests 324/324, compile clean. Also confirmed repetition_penalty doesn't trip bodyRequestsThinking(), so the Go gateway #37635 workaround path is unaffected.

Context for anyone reading later: this is a third mitigation on top of what we shipped for #36 (budget_tokens cap + suffix-repetition detection in the stream extractor). A sampling-level penalty makes sense, and applying it with reasoning off matches the upstream analysis, the loop just fires less often there.

Two things:

1. Checklist says "I updated docs/CHANGELOG" but the diff doesn't touch CHANGELOG.md. Can you add an entry? Happy to handle it on merge if that's easier, just let me know.

2. Small nit, not a blocker: consider pulling 1.2 into a named constant next to MIMO_BUDGET_MAP (e.g. MIMO_REPETITION_PENALTY) so it reads as a tuning knob instead of a magic number. Fine to keep inline if you prefer.

Once the CHANGELOG entry is sorted I'll merge with a merge commit so your three commits stay intact.