Get providers with their configuration and metadata.
Query params:
Returns full provider details including name, icon_url, has_cloud_api, is_enabled.
Return only enabled providers
Return only cloud (OAuth) providers
Successful Response
Provider identifier (e.g., 'apple', 'garmin')
Display name (e.g., 'Apple Health', 'Garmin')
Whether provider uses cloud OAuth API
Whether provider is enabled by admin
Relative URL to provider icon (e.g., '/static/provider-icons/garmin.svg'). Resolve against the API base URL.