Copilot is the only AI provider type that could not be added through the `/ai/settings` UI. The aibridge runtime and the env-var seeding path already supported it, but the runtime CRUD API rejected `type=copilot` and the UI omitted it entirely. The root cause is that Copilot's auth model (a per-request GitHub OAuth token, with no pre-shared key) does not fit the credential-centric add-provider flow that every other provider uses.

## Backend

Allow `type=copilot` in `CreateAIProviderRequest.Validate()`, and reject `api_keys` for Copilot on both create (validation) and update (handler sentinel), mirroring the existing Bedrock guards. Copilot carries no stored credential.

## Frontend

Add Copilot to the provider type picker (with the `github-copilot.svg` icon) and give the form a credential-free branch: name, display name, and a free-text endpoint defaulting to `https://api.business.githubcopilot.com`, with copy explaining that authentication happens via the user's GitHub token at request time. Copilot maps to the distinct `copilot` wire type rather than collapsing to `openai`, and the edit flow recovers it correctly.

The endpoint stays required with a business-tier default; users on the individual or enterprise endpoints edit the field.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

(cherry picked from commit a85462b)