feat(althing): move the post office to nh3-docker

Operator directive, and a standing goal: the bus belongs on the docker
host. The flag-day deployment put it on nh3-dev because the herald lives
there -- but the herald is the piece that must be host-local, and the
post office is explicitly the piece that is not.

nh3-dev was wrong on three counts. Our own server table calls it "not a
Docker-stack host". It has had three OOM events in fourteen days with
the interval halving, and the confirmed hog is Claude Code sessions at
5-18 GB, which is that box's actual job. And mem_limit protects the
fleet from the post office while doing nothing in the other direction:
oom_score_adj was 0, an ordinary kill candidate, on a box whose last
sweep took althing-herald and uvicorn. The new deployment sets
oom_score_adj=-500.

The compose is now version-controlled here as a normal stack rather than
living only in the althing repo's deploy dir.

## docker stop does not checkpoint the WAL

The database was 155 KB with a 4.1 MB write-ahead log, and every recent
message was in the log. A clean container stop left it untouched -- an
explicit PRAGMA wal_checkpoint(TRUNCATE) was required.

A docker cp of the .db alone would have produced a database that opens
cleanly, passes integrity_check, serves the full 73-handle roster, and
is missing the day's mail, with nothing raising an error. Row counts
were verified at source, in the staged copy, and after seeding, because
the count is the only thing that separates those two outcomes.

The old volume is left in place. Not a rollback path, which the operator
ruled out -- just not deleting the only other copy on the day of a move.

## Follow-up left open

The image has no registry push and moves by save/ssh/load, so a rebuild
means repeating that by hand. It should join the gitea registry pattern
the other stacks use.

persistent-memory.md

@@ -27,7 +27,7 @@ Sister repos (separate gitea repos, deployed by playbooks here):
 | `vh/vor` | Inquisitor UI sidecar (port 7879) | push-to-main → CI deploys (2026-04-29) |
 | `vh/nevermore` | Twice-daily LLM-curated briefing (port 8181, replaces news-digest) | push-to-main → CI deploys (2026-04-30) |
 | `vh/asset-engine` | Internal control plane over inference services (port 8200, LAN-direct) | push-to-main → CI deploys (2026-05-12) |
-| `vh/althing` | Lean trusted inter-agent message bus — **v3.0.0 "the post office" as of 2026-08-28 (U9b flag day, one-way, no rollback)**: ONE container on nh3-dev at `http://10.100.10.50:8390` is the only stateful component; `althing-po-herald` one per box; `althing-listen` one per session; `postbox` is the client. **Every v2 command was DELETED, not deprecated** — `althing-cli`→`postbox`, `althing-wake-listener`→`althing-listen`, `althing-light-monitor`/`althing-receiver` gone. Sessions need BOTH `ALTHING_POST_OFFICE` and `ALTHING_HANDLE`; there is no default address. ⚠ An unreachable post office is an OUTAGE, never an empty inbox. → `persistent-memory.d/2026-08-28-althing-v3-cutover.md` | per-box install (NOT CI-deploy); **nh3-dev** = container host + repo; **nh3-extdev** = system WHEEL at `/opt/uv-tools`, needs its own wheel install (`playbooks/nh3-extdev-althing-v3.yaml`) |
+| `vh/althing` | Lean trusted inter-agent message bus — **v3.0.0 "the post office" as of 2026-08-28 (U9b flag day, one-way, no rollback)**: ONE container on nh3-dev at `http://10.100.50.40:8390` is the only stateful component; `althing-po-herald` one per box; `althing-listen` one per session; `postbox` is the client. **Every v2 command was DELETED, not deprecated** — `althing-cli`→`postbox`, `althing-wake-listener`→`althing-listen`, `althing-light-monitor`/`althing-receiver` gone. Sessions need BOTH `ALTHING_POST_OFFICE` and `ALTHING_HANDLE`; there is no default address. ⚠ An unreachable post office is an OUTAGE, never an empty inbox. → `persistent-memory.d/2026-08-28-althing-v3-cutover.md` | per-box install (NOT CI-deploy); **nh3-dev** = container host + repo; **nh3-extdev** = system WHEEL at `/opt/uv-tools`, needs its own wheel install (`playbooks/nh3-extdev-althing-v3.yaml`) |
 | `vh/mead-hall` | Bifrost tool-provider sidecar (port 5173 on dev VM 10.100.10.50) | push-to-main → CI deploys (2026-05-16) |
 | `vh/skaldsong` | Wizard + reader surface (port 8300, ana-docker, registry-pull pattern) | push-to-main → CI deploys (2026-05-19) |
 | `vh/Worldtree` | Conversation API (corviduo-dev demo :8080 / personal :8081 / pinned :8082) — Heimdall auth, Bifrost integration. **gitea-runner builds on ana-docker**; claude-bot ADMIN collaborator (2026-06-20). Now v1.0.0b19. | push-to-main → CI build-and-deploy (runner on ana-docker) |