v0.16.1

Released 2026-09-17. Every package in the workspace moves to 0.16.1 together.

• dg secret-key generates the envelope key. It writes a DIRIGENT_SECRET_KEY and
  nothing else, on one plain line at a terminal and in a pipe alike, so
  DIRIGENT_SECRET_KEY=$(dg secret-key) works in a shell and in a .env. It is the second
  plain-line command beside dg --version; every other command still writes records in a
  pipe. The README, .env.example and the docs name it where they used to show a python
  one-liner, and dg init, dg run --local and the dev seed mint their keys through the
  same generator.
• HTTP 429 is transient. status_class in the http blocks and the plugin's default
  classifier treated every 4xx as rejected, so a rate-limited step was never retried. A 429
  now sits beside 5xx; every other 4xx stays rejected.