feat: add MiniMax as LLM provider

[octo-patch]

Summary

• Add MiniMax as a first-class LLM provider with MiniMax-M2.7, MiniMax-M2.5, and MiniMax-M2.5-highspeed models
• New MiniMaxEngine extending OpenAiEngine using OpenAI-compatible API at api.minimax.io/v1
• Full setup wizard integration: provider display, API key URL, recommended model, dynamic model fetching

Changes

File	Change
src/engine/minimax.ts	New MiniMax engine with think-tag stripping, low temperature for deterministic output
src/commands/config.ts	MINIMAX enum value, model list, API key URL, recommended model, validator
src/utils/engine.ts	Engine factory case for MiniMax
src/utils/errors.ts	Billing URL and recommended model for error recovery
src/utils/modelCache.ts	fetchMiniMaxModels() with /v1/models endpoint, cache integration
src/commands/setup.ts	Provider display name, listed in OTHER_PROVIDERS
README.md	Added minimax to provider list and config example
test/unit/minimax.test.ts	32 unit tests covering all integration points
test/unit/minimax-integration.test.ts	3 integration tests (M2.7, M2.5-highspeed, auth error)

Usage

oco config set OCO_AI_PROVIDER=minimax OCO_API_KEY=<your_minimax_api_key>

Or use the interactive setup wizard:

oco setup
# Select "Other providers..." → "MiniMax (M2.7, M2.5, fast inference)"

Test plan

• 32 unit tests pass (npm run test -- test/unit/minimax.test.ts)
• 3 integration tests pass with live MiniMax API (MINIMAX_API_KEY=... npm run test -- test/unit/minimax-integration.test.ts)
• Existing tests pass with no regressions (test/unit/config.test.ts, test/unit/removeContentTags.test.ts)
• Manual: oco setup → select MiniMax → generate commit message

[di-sukharev]

hello @octo-patch please merge master into your branch to solve the confict and i will merge it

[di-sukharev]

First-class MiniMax support is useful, but this PR conflicts with master, and both the end-to-end and Prettier checks fail. After rebasing, please update the models and endpoint against the current API, and replace tests that read source files and search for strings with behavioral engine/request tests. Live integration tests should be opt-in and must not depend on a secret in regular CI.