Create a live data source such as an RSS feed or flight board

Creates a content source that InfoSlides fetches (RSS feed, weather, flights, calendar, custom text): {"adapterType": "RssFeed", "name": "News", "config": {"feedUrl": "https://example.com/rss"}, "fetchIntervalSeconds": 900}. GET /v1/adapters lists each adapter's configFields; config is validated against them. fetchIntervalSeconds defaults to 3600; lower values than 300 are raised to 300. Fetching sources need a paid plan (EntitlementRequired with upgradeUrl otherwise); a Push source is made by adding a push template's slide with POST /v1/slideshows/{id}/slides/dynamic.