v0.3.0

Fixed

• A drained backlog no longer refuses new mail when the store has reusable
  pages. Disk admission and doctor count that space while reserving room
  for the write-ahead log. store_reusable_bytes exposes it.
• A disk too full to check the store reports that the check could not finish
  instead of calling the store damaged and recommending a backup restore.
• Unsigned external feedback for a message sent to several recipients no
  longer suppresses or counts against any of them. An authenticated copy can
  still apply its effects once; reports for one-recipient messages and a
  transport's own delivery-scoped reports keep their existing behaviour.
• Outbound SMTP negotiates 8BITMIME. A receiver without it still takes 7-bit
  mail; 8-bit content fails locally before MAIL, without suppressing an
  address or counting the failure as the receiver's reputation signal.
• Release builds require the Rust gate and the official SDK matrix to pass
  at the release tag. The README capture example includes identity setup,
  credentials and certificate trust.
• Container releases publish the latest tag as well as the version tag,
  so the unversioned image reference resolves to the current release.

Added

• [receivers.<Provider>.warmup] promote = false holds automatic cap increases
  for that provider while keeping automatic reductions. The hold is visible
  in nitromta list; other providers continue warming independently.