Mission mode orchestrator defaults to Claude Opus 4.6 instead of default model if default model is BYOK/custom

[Algorith0n]

Steps to reproduce:

1. Set default model to BYOK/Custom model
2. Start Factory Droid
3. Type /enter-mission
4. Orchestrator model sets to Claude Opus 4.6

If default model != BYOK/Custom model, Orchestrator model = default model instead.