Implements intelligent model selection based on available providers.
Priority order: Native > Copilot > OpenCode Zen > Z.ai > Ultimate Fallback.
- Add model-fallback.ts with MODEL_CATALOG and capability-based resolution
- Extend InstallConfig with hasOpencodeZen and hasZaiCodingPlan
- Add TUI prompts and CLI args for new provider options
- Z.ai gets Librarian priority (zai-coding-plan/glm-4.7)
🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)
- Remove chatgpt option from CLI args and types
- Remove ChatGPT prompt from TUI installer flow
- Update config detection to not include hasChatGPT
- Update related tests
Add GitHub Copilot as a fallback provider option in the installer. Native providers (Claude/ChatGPT/Gemini) have priority over Copilot.
- Add hasCopilot field to InstallConfig and DetectedConfig types
- Add --copilot flag support for both TUI and non-TUI modes
- Add Copilot prompt in interactive installer (after Gemini)
- Update model selection logic to use Copilot fallback when native providers unavailable
- Update configuration summary to display Copilot status
Addresses #762
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
