v0.1.0 of base_idp

Official Flutter and Dart SDK for Base IdP OAuth PKCE login and server handoff. Changelog excerpt: # Base IdP Flutter/Dart SDK Official Flutter and Dart SDK for Base IdP authentication. Base IdP owns identity. Your app owns product data. This SDK connects a Flutter or Dart app to the hosted Base IdP authorization UI, discovers the client configuration from Base IdP, runs OAuth authorization-code flow with PKCE, fetches the authenticated principal, and returns a server handoff payload that your backend can verify and merge with its own user records. ## What This SDK Solves Most apps should[...]