v1.0.0-beta.8

Added

• OTelFactory.isAPIFactory — identifies the API's auto-installed no-op
  factory. Defaults to false on OTelFactory; OTelAPIFactory overrides it
  to true. SDK factories (which extend OTelAPIFactory) must override it to
  return false. Lets SDK initialization replace the spec-mandated no-op API
  factory installed when API code runs first, instead of relying on
  runtimeType checks (see dartastic_opentelemetry #50 / PR #53).

Fixed

• Context.root / Context.current (and other Context APIs) threw
  StateError('Call initialize() first.') when accessed before
  OTelAPI.initialize(), violating the OTel spec requirement that the API
  operate as a no-op without an SDK installed. They now lazily install the
  No-Op API factory, matching OTelAPI's existing behavior. Thanks
  @benjaben.
• Context re-reads the global factory on every access instead of keeping
  the first one it saw, so a factory installed later (e.g. by an SDK's
  initialize()) replaces a no-op cached before initialization.
• OTelAPI.initialize() now replaces an installed no-op API factory
  (isAPIFactory == true) instead of throwing, so API use before
  initialization (e.g. Context.current) no longer blocks explicit
  initialization. Behavior change: re-initializing over a no-op API
  factory replaces it and applies the new configuration; only a real
  (non-API) factory still triggers the initialize-once StateError.