Release 0.32.0

Version bump only. Everything in this release landed in
#24.

Minor rather than patch: two migrations, and behaviour that changes on
upgrade.

What it fixes

A code review of the 0.31.0 tag found 28 defects. The three worst:

• The public outbox published the member-identity channel, so a
  crawler could turn a pseudonymous upload history into a name and a home
  instance with one join.
• Any partner accepting the accounts channel could credit any member,
  for any window, twice.
• An erased account got a fresh signing key on the next mint sweep, and
  erasure had never reached the catalogue this instance serves.

Before upgrading

Two migrations, 0043 and 0044. Both additive, both applied at boot.

FEDERATION_REQUIRE_AUDIENCE now also governs relay
countersignatures. Nothing to do — records carry both the bare and the
bound proof, so a mesh mid-upgrade works in both directions and the flag
stays off. Turning it on before every partner runs this build stops
accepting their relayed records silently: a refused record is sourced as
rejected and never asked for again, so the catalogue just stops growing.
doc/guide/upgrading.md has the detail.

🤖 Generated with Claude Code

What's Changed

• Fix everything the 0.31.0 code review found by @Dim145 in #24
• chore(release): 0.32.0 by @Dim145 in #25

Full Changelog: 0.31.0...0.32.0