When users logged in via /login but never explicitly ran /model, the agent
would throw 'No model configured' on every action. Now GSD auto-selects
a default model from available authenticated providers on startup.
Preference order: claude-sonnet-4-20250514 > any Anthropic model > first available.
Also documented /model command in README Getting Started section.
Closes#4
These extensions were removed from the repo but the loader still
referenced them and the README still listed them. Removed from:
- src/loader.ts extension entry points (11 → 9)
- README bundled extensions table
- app-smoke test assertions
- 20+ built-in providers (Anthropic, OpenAI, Google, OpenRouter, etc.)
- OAuth support for Claude Max, Codex, GitHub Copilot subscriptions
- OpenRouter for access to hundreds of models
- Per-phase model selection example in preferences
- Updated requirements to note Node 22+ recommended
