Review: three ADRs no longer said what we had concluded

A sweep for claims overtaken by the last few days. Annotated rather than
rewritten, following the pattern already in 0049 -- what changed and why is the
useful part, and an accepted record should not quietly become something else.

0057's init section was wrong on all three of its claims. It said the host
needs FOUR things from an init; 0061 reduced that to one. It said every machine
the mesh targets already has systemd; Alpine does not, and it is the intended
first node. It said there is no second init to abstract over; there is now, and
the answer is still not an abstraction -- it is a four-line file per system.
What survives is the part that was always right: an init is not a dependency in
0041's sense, because it is not installed, it is what the machine already is.

0048 named Docker as the container runtime. It is now docker or podman,
detected rather than chosen -- because adoption keeps what a machine already
has, so naming one contradicted a rule already decided. That row is the only
one of the five that names two, and the record now says why.

0060 claimed the bundle is portable across operating systems. Its mechanism is;
its contents are not -- package names, unit names, service names all differ, so
an Arch host embeds an Arch bundle. That was my error, and it is the exact
confusion behind the question that found it.

The design layer had the same drift: 07 and 09 said "Docker" where they meant a
container runtime, 09 said systemd restarts the host after an upgrade when the
launcher does, and both install snippets assumed Arch. They now show Alpine and
Arch side by side, which makes the point better than prose did -- step 1
differs per system, step 2 never does.

Checked and NOT changed: 0047's "the vocabulary grows by one shape" is a claim
about the rate, not the count, and is still true. 0037 lists docker among tools
the host manages, which it does. 0041 says nothing about either.

02-DECISIONS/0048-the-substrate-is-named.md

@@ -40,7 +40,7 @@ Two costs, both already accrued:
 | message bus | **LavinMQ** | In use, speaks AMQP, which is what [ADR 0001](0001-nodes-communicate-over-a-broker.md) assumes. Interchangeable with other AMQP brokers at the protocol level, which is what makes it a safe choice rather than a locked-in one. |
 | object store | **MinIO** | In use, speaks the S3 protocol, which is the closest thing to a portable object-store interface. |
 | image registry | **the OCI distribution registry** | In use, and the format is the standard rather than a vendor's. |
-| container runtime | **Docker** | In use. Podman is the plausible alternative and was not chosen for any deficiency — Docker is what the machines run today and what the current tooling assumes. |
+| container runtime | **Docker or Podman** — *detected, not chosen* | See below. The other four rows name one product; this one names two, and the difference is the point. |
 
 ### Outside the substrate
 
@@ -58,6 +58,15 @@ correction applies — a role is a legitimate abstraction, but the product belon
 a route is an ordinary grant. Recorded here because finding it was the point — naming the
 products is what made the unnamed role visible.
 
+**The container runtime is the one row that is not a choice at all**, and it stopped being one
+after this record was written ([ADR 0060](0060-the-host-is-built-per-operating-system.md)). The
+host detects what the machine has and uses it, because adoption keeps a machine's existing
+configuration rather than replacing it — so naming a single runtime here contradicted a rule
+already decided. Both are supported, checked against a real podman: only the version probe
+differs, and one behavioural difference (podman has no daemon, so containers do not return after
+a reboot unless `podman-restart.service` is enabled) belongs in the declaration rather than the
+host.
+
 **Identity is deliberately absent.** Whether an identity provider is substrate at all depends on
 whether the control plane delegates authentication, which is undecided
 ([`07-the-substrate.md`](../03-DESIGN/01-to-be/07-the-substrate.md)). Naming a product before