* fix(providers): switch minimax from claude to openai format so images work
The Anthropic-compatible /anthropic/v1/messages endpoint rejects image
input with 403. MiniMax's OpenAI-compatible /v1/chat/completions endpoint
supports image_url natively for MiniMax-M3.
- minimax + minimax-cn: format claude→openai, baseUrl→/v1/chat/completions
- Remove Anthropic-Version header + ?beta=true suffix (not needed for openai)
- Remove minimax/minimax-cn from ?beta=true executor case
- Update cache-control tests (openai format uses different caching path)
- Fix reasoning-split test names (no longer claude format)
TDD: 2 registry tests assert format=openai (red→green).
Refs: Hermes Agent #15715, MiniMax OpenAI-compatible API docs.
* fix(sse): re-align stream-readiness-policy tests with minimax's openai format
PR #9463 switched minimax/minimax-cn from claude to openai format so images
work. The stream-readiness bump for Claude-format replicas is keyed off the
registry's format field (single source of truth), so minimax legitimately
falls out of that group now. Swap the "Claude-format replica" test fixtures
to agentrouter (still format: "claude") and add explicit coverage that
minimax no longer gets the claude_format_heavy_reasoning bump.
---------
Co-authored-by: diegosouzapw <diegosouzapw@users.noreply.github.com>
c61cdc30aa