- Change skills type from string[] | null to string[]
- Allow skills=[] for no skills, reject skills=null
- Remove emojis from error messages and prompts
- Update tests accordingly
Previously, parent model string would override category default model,
causing categories like 'ultrabrain' to use the parent's model (e.g., sonnet)
instead of the intended category default (e.g., gpt-5.2).
Model priority is now:
1. userConfig.model (oh-my-opencode.json override)
2. defaultConfig.model (category default)
3. parentModelString (fallback)
4. systemDefaultModel (last resort)
