feat: add MiniMax M2.5 model

[roomote]

Related GitHub Issue

Closes: #11471

Description

This PR attempts to address Issue #11471 by adding the MiniMax M2.5 model to the supported models list. Feedback and guidance are welcome.

Changes:

• Added MiniMax-M2.5 entry to minimaxModels in packages/types/src/providers/minimax.ts with specs matching the M2 series (192K context, 16K max output, prompt caching, reasoning support)
• Updated minimaxDefaultModelId to MiniMax-M2.5 since it is the latest model
• Added test coverage for the new M2.5 model configuration
• Updated the default model assertion test to expect MiniMax-M2.5

No handler changes were needed since minimax.ts is model-agnostic.

Test Procedure

• Ran npx vitest run api/providers/__tests__/minimax.spec.ts from src/ directory -- all 24 tests pass
• Lint and type checks pass via pre-push hooks

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue.
• Scope: My changes are focused on the linked issue.
• Self-Review: I have performed a thorough self-review of my code.
• Testing: New and/or updated tests have been added to cover my changes.
• Documentation Impact: No documentation updates are required.
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

Documentation Updates

• No documentation updates are required.

Additional Notes

Model specs for M2.5 were confirmed by the issue reporter as matching the existing M2/M2.1 series:

• Context window: 192,000 tokens
• Max output: 16,384 tokens
• Pricing: $0.30/$1.20 per million input/output tokens
• Cache writes: $0.375, cache reads: $0.03
• Supports prompt caching and reasoning preservation

Interactively review PR in Roo Code Cloud

[roomote]

Rooviewer   See task

Reviewed fa34b5b -- found 1 issue. The M2.5 model entry uses M2's contextWindow and maxTokens instead of the actual M2.5 specs from the issue.

• packages/types/src/providers/minimax.ts: M2.5 contextWindow should be 204,800 and maxTokens should be 131,072 per the model card and [ENHANCEMENT] add model minimax -m2.5 #11457. MINIMAX_DEFAULT_MAX_TOKENS should also be updated.

Previous reviews

• 40ed6dc: Review #1

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