Add MiniMax model provider

[octo-patch]

Reason: add target provider/model to existing provider registry

Summary

• Add MiniMax-M3 and MiniMax-M2.7 to the existing model registry with verified context, modalities, thinking behavior, tiered pricing, and regional endpoint guidance.
• Route the MiniMax registry entry through the existing compatible chat adapter and support the published Anthropic-compatible base URLs without exposing a versioned API root.
• Add a dedicated provider icon and focused tests, including a captured /anthropic/v1/messages request.

Verification

• AIRAG Java 17 reactor compile: passed.
• AIChatHandlerTest: 5 passed.
• pnpm run build: passed.
• pnpm exec prettier --check src/views/super/airag/aimodel/icon/minimax.svg: passed.
• JSON, SVG, target-matrix, and git diff --check validation: passed.