GitHubModelsClient now lazily resolves tokens at first API call. If no
token exists (env var, stored OAuth, or config), it triggers the OAuth
device flow automatically via an onLoginRequired callback wired in both
the TUI and daemon entry points.
Add a new 'github' model provider backed by the Copilot API
(api.githubcopilot.com), with OAuth device flow for authentication.
- New src/auth/github.ts: device flow login, token storage at
~/.config/flynn/auth.json with 0600 permissions
- New src/models/github.ts: OpenAI-compatible client with streaming,
tool calling, and Copilot-specific headers
- Add 'github' to provider enum in config schema
- Register provider in daemon factory and TUI client factory
- Refactor TUI to use provider-agnostic client factory (was hardcoded
to AnthropicClient for all tiers)
- Add /login command to TUI for interactive OAuth authorization
- Add Copilot model cost tracking entries
William Valentin