v3.0.0

v3.0.0 — one anchored value, through the authenticated proxy

Every port now anchors the same composite, and the parity digit is
derived rather than random, so the whole 72-character payload is
reproducible from the archive alone.

Ports post to POST /api/commit-ideas/glue with the token they already
held, instead of straight to timeglue with a userID and no token.
Release binaries carry the production API URL via -ldflags -X; before
this, a downloaded binary pointed at localhost.

Dependencies: 13 advisories (2 critical) down to 3.

Breaking: the on-chain payload changes meaning. See the anchor-format
table in the README before verifying older stamps.