v0.31.0 — agent-stack

• test/family_gate.py, the family's canonical member gate (hub B-108, B-109): the board
  parses (every row as wide as its header, no id twice) and release.yml keeps the tag-ancestry
  check (fetch-depth: 0, git merge-base --is-ancestor), each watched failing on a plant by
  --self-test. Wired into the gate; a byte-for-byte copy of the hub's member-gate/family_gate.py.
• agent-evals references/support-quality.md: the support quality standard v1 for agents
  that answer people (issue #56). The per-turn record (A1); four metric families per channel
  per closed UTC day, a metric not computed is "not measured", never 0 (A2); first-reply p90
  targets per channel kind: private chat under 30 s, mail under 4 h, store reviews under 24 h,
  group chats within the agent's come-back window; first reply measured from the person's
  message to the sent reply; rubric v1 and why factual accuracy is not the judge's job (A3);
  the judge, from another vendor, alerting on a check only after 80% human agreement (A4);
  support.quality_daily, counts and codes only (A5); autonomy without blocking (A6);
  portability (A7). Plus the weekly assessment loop (findings with cause class, owner,
  action and priority, compared by finding id), the checks that caught real defects, and
  one deployment's baseline labelled as a measurement, not a target. Routed from the
  agent-evals references table and an agent-orchestrator checklist line.
• test/validate.py: check_support_standard_keeps_its_parts (four self-tests) fails
  when the standard loses a part heading A1 to A7, a channel kind's target row, or the
  "never 0" rule in A2 or A5.
• README: the reference count reads 32 (it read 27 while 31 shipped; agent-harness 10,
  not 7).