Part of the V1.md Track 1 non-breaking 0.x modernization work. Add promise-native storage and metadata adapter contracts and APIs while retaining callback compatibility, normalize legacy custom adapters for registry internals, and emit one-time callback deprecation warnings. Cover official and custom adapters, successful operations, callback compatibility, and adapter errors without changing component or browser contracts.
Part of the V1.md Track 1 non-breaking 0.x modernization work. Add promise-native storage and metadata adapter contracts and APIs while retaining callback compatibility, normalize legacy custom adapters for registry internals, and emit one-time callback deprecation warnings. Cover official and custom adapters, successful operations, callback compatibility, and adapter errors without changing component or browser contracts.