Add MiniMax model provider support

[octo-patch]

Reason: Add first-class MiniMax model provider support for workspace vendor selection.

Changes:

• Added MiniMax model metadata with global and CN OpenAI-compatible and Anthropic-compatible endpoint defaults.
• Added MiniMax to runtime settings validation, adapter descriptors, provider testing, and runtime model config generation.
• Added console defaults so the setup flow can select MiniMax without manual generic-provider wiring.

Checks:

• npm test -- tests/unit/settings.test.ts tests/unit/runtime-settings-forms.test.tsx
• ./node_modules/.bin/tsc --noEmit --pretty false
• ./node_modules/.bin/tsc --noEmit -p tsconfig.tests.json --pretty false