v0.1.0

• Initial release: FirebaseAuthSession (Identity Toolkit sign-in +
  Secure Token refresh + session persistence), GoogleDesktopOAuth
  (loopback + PKCE), Firestore (get/create/set/delete/list/runQuery +
  polling change stream), and FirestoreValueCodec.
• Firestore.commitUpdate: masked updates through documents:commit with
  atomic array transforms (appendMissingElements/removeAllFromArray, the
  REST equivalents of arrayUnion/arrayRemove) and an optional
  exists: true precondition.
• FirestoreApiException carries the canonical status name and an
  isNotFound helper; batch-endpoint error arrays are parsed.