v0.3.0

• Breaking: seven error classes and sixteen EncryptionErrorCode members are
  removed, because nothing in the library ever threw them. Each class was
  exported and paired with a type guard, so an application could branch on it —
  but no code path constructed any of them, which made every one of those
  branches dead code that read as handled. Removed, with their is* guards:
  IdentityKeyChangedError, SessionConflictError,
  RegistrationIdChangedError, and the four intermediate classes
  CryptoError, SessionError, ProtocolError and ClientError. Removed
  codes: IDENTITY_KEY_CHANGED, IDENTITY_KEY_ERROR, SESSION_CONFLICT,
  REGISTRATION_ID_CHANGED, INVALID_REGISTRATION_ID, MESSAGE_TOO_OLD,
  INVALID_MESSAGE_VERSION, RATCHET_ERROR, DATABASE_ERROR,
  DATABASE_LOCKED, KYBER_ERROR, KDF_ERROR, HMAC_VERIFICATION_FAILED,
  SPQR_KEY_ALREADY_USED, SPQR_EPOCH_REGRESSION and UNKNOWN_ERROR. The
  enum goes from 49 members to 33.

  What to use instead: an identity that changed is an identity that is not
  trusted, and the library throws UntrustedIdentityError /
  UNTRUSTED_IDENTITY for it from five sites on the session and sending
  paths. Code branching on isIdentityKeyChangedError or on
  IDENTITY_KEY_CHANGED was never reached and should branch on
  isUntrustedIdentityError instead. The other removed names have no
  replacement, because there was no event behind them.

• UntrustedIdentityError and isUntrustedIdentityError are exported from
  the package root. They were reachable only from
  @open-e2ee/signal-protocol-sdk/types/errors, while the error-handling guide
  imported them from the root — so the first thing a reader copied did not
  resolve. StorageQuotaExceededError also gains the
  isStorageQuotaExceededError guard its five siblings already had.

• Every documented error code is now traceable to a construction site. A
  check parses the library for the sites that decide whether a class can be
  thrown, and fails the build when an exported error class or a declared code
  survives with none — so the surface cannot drift back. Being named in a
  switch counted as use before, which is what hid IDENTITY_KEY_CHANGED
  through all nineteen releases that declared it and never threw it.