Add MiniMax provider

[octo-patch]

Reason: Add MiniMax provider support with regional endpoint selection and current MiniMax model blueprints.

Changes:

• Added a MiniMax provider package with MiniMax-M3 and MiniMax-M2.7 metadata, global and China endpoint selection, chat response extraction, image message formatting, and tool-call flow.
• Added matching multi-provider blueprint files for MiniMax.
• Added focused tests for MiniMax model metadata and endpoint resolution.

Checks:

• uv run --with 'ruff>=0.9.7' --python 3.11 ruff check
• uv run --with 'pytest>=7.2.1' --with 'pixeltable>=0.3.15' --python 3.11 pytest tests/test_minimax.py -q
• python3 -m py_compile

[octo-patch]

I fixed the import ordering in the MiniMax blueprint test and pushed a new commit. I ran pytest -q tests/test_minimax.py (4 passed) and ruff check on all changed Python files.