Release all six architectures

[talaria0101]

v0.2.2 shipped only x86_64 and aarch64 because the release workflow's
matrix, its collect step and its checksum step still enumerated two
architectures, and because scripts/release-notes.sh refused to generate
a body from manifests whose floors disagree, which they now do by
design: loongarch64's floor is glibc 2.36, the first release that runs
the architecture, against 2.31 everywhere else.

Widen all three to x86_64, aarch64, riscv64, ppc64, ppc64le and
loongarch64, and state the floor per architecture in the generated body
instead of once. The refusal survives in the scope where it was a
finding: the two variants of ONE architecture must still agree.

The collect step now refuses in both directions. Missing staged
artifacts already refused; an architecture that produced artifacts but
is not in the collect list now refuses too, so a matrix row added
without widening this list cannot ship a release that silently lacks
it, which is the shape v0.2.2 had.

Measured locally, with real builds:

• five cross builds plus one portable, packaged by package-release.sh;
  release-notes.sh generates the body from all six manifests with the
  per-arch floor table (aarch64 2.31 ... loongarch64 2.36), where the
  previous script exits 2 on the same input.
• planted defects, each seen to refuse: two manifests of one
  architecture disagreeing about the floor (exit 2); an unlisted s390x
  in staged (exit 1); a missing architecture (exit 1); one corrupted
  byte in a loose ppc64 asset against its manifest (exit 1, and 25 of
  25 pass clean).

The evidence gate is unchanged and still blocks every architecture: it
runs where it can, on the two architectures with runners, and the four
cross-compiled ones are released on the build verification, which the
workflow header now states with the pointer to
docs/report/10-measured-versus-assumed.md 10.

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Requested by Samueru via pi-discord.
Conversation: https://discord.com/channels/1313385177703256064/1545249294377033729
Transcript: https://talaria.qaidvoid.dev/?session=1i2d05e