[togetherai] Require reasoning options metadata

[rekram1-node]

Summary

• add reasoning_options = [] to the three Together AI reasoning models that lacked the mandatory field
• cover Google Gemma 4, Pearl Gemma 4, and deprecated MiniMax M2.5
• preserve all verified non-empty controls and existing fixed arrays; reasoning-disabled models continue to omit options

An empty array means reasoning capability is known, but the exact provider controls remain unspecified under the mandatory-field policy.

Validation

• bun validate
• generated Together invariant scan: 18 reasoning models, 5 empty arrays, 13 non-empty controls, 0 missing options, 0 reasoning-disabled models with options
• git diff --check
• diff scope: 3 Together TOMLs, 0 test paths