0.2.1

• Two GitHub code-scanning findings in shipped code are fixed. The
  URL-safe base64 conversions stripped trailing = padding with a /=+$/
  replace, which backtracks quadratically on input that is mostly =
  characters; padding is now stripped by index in linear time. The Node
  store's getKey probed the key file with access() before reading it,
  leaving a race window between the check and the read; it now reads
  directly and treats ENOENT as an absent key. Neither fix changes
  observable behavior on well-formed input. The scan's prototype-pollution
  alerts against the Node sender-key trees were confirmed false positives:
  every decoded dictionary level is rebuilt with a null prototype before it
  is indexed, and the full-interface tests already prove __proto__ keys
  round-trip as plain data.

• Vulnerable development-dependency versions are updated. js-yaml,
  nanoid, postcss, and brace-expansion move past their published
  denial-of-service advisories. The two image-size advisories have no
  fixed release yet; they sit behind Metro's dev-time asset parsing and do
  not reach the published package, whose production dependencies audit
  clean.

• @noble/ciphers moves to 2.3.0. A routine minor update of the
  symmetric-cipher dependency, applied internally so the public Dependabot
  pull request can close against this release.