[octo-patch]

Reason: Keep the MiniMax model registry aligned with the current reasoning-mode and effort metadata.

Summary

• add MiniMax-M3.1-Flash with a 1M context window, text/image/video input, always-on adaptive reasoning, and low through max effort presets
• keep MiniMax-M3 at a 1M context window with text/image/video input, adaptive or disabled reasoning, and protocol-specific defaults
• remove the stale MiniMax-M2.7 registry entry and retain the global and China OpenAI/Anthropic endpoints
• verify the exact model set, reasoning metadata, protocol defaults, modalities, endpoints, and registry offers

Checks

• go test ./cmd/moonbridge ./internal/protocol/anthropic
• CGO_ENABLED=0 go test ./...
• CGO_ENABLED=0 go build ./...
• git diff --check