Approve 0054-0056, apply them, and fix the two smaller findings

0003 is now superseded by 0056. Nothing is left proposed.

Applied:
- 06 corrected from ten contexts to seven plus the api, each row now stating
  why it passes the more-than-one-node test. work, knowledge and stream are
  named as mesh-hosted rather than dropped; `ai` folds into config; `record`
  is deferred explicitly rather than listed. Its frontmatter now cites 0055.
- how-we-build §4 amended per 0054, and the derived page republished by
  playbook 05.

The sync found the drift the playbook exists to catch: the published §4 and
the source did not say the same thing. The source said "four accidents, not
four boundaries"; the published page said "one intent expressed four times",
and only the published page carried the scope caveat. Same rule, two texts,
already diverging. Verified the republish by reading back -- the new rule is
present and the old section's body returns nothing -- rather than trusting the
success message.

The two smaller findings:
- 0051 separated the transport identity from the declaring authority. It said
  the token carries "an address" and "the identity to expect" without saying
  what the node dials. It dials the broker, so pinning only that would make the
  control plane's authority transitive and let a compromised broker forge
  declarations -- which, since the host applies whatever the link delivers, is
  the whole machine. The token now carries four things, and declarations are
  signed and verified per declaration. Cost recorded: rotating the signing
  identity is fleet-wide.
- 0026 no longer restates 0022's rule about generated views. 0022's own words
  are "prose does not restate status; one place, and two is one too many",
  which is what 0026 was doing to it.

03-DESIGN/01-to-be/README.md

@@ -17,14 +17,15 @@ document is written and this one's status becomes `implemented`.
 | [`05-the-node-host.md`](05-the-node-host.md) | Tier 0 — the one thing installed by hand, and the only thing that changes a machine | [ADR 0037](../../02-DECISIONS/0037-the-host-applies-it-does-not-decide.md) |
 | [`06-the-control-plane.md`](06-the-control-plane.md) | Tier 2 — what the term means, and the test for what belongs in it | [ADR 0037](../../02-DECISIONS/0037-the-host-applies-it-does-not-decide.md) |
 | [`07-the-substrate.md`](07-the-substrate.md) | Tier 1 — what the control plane consumes and cannot grant itself | [ADR 0038](../../02-DECISIONS/0038-a-node-joins-by-linking-first.md), [0048](../../02-DECISIONS/0048-the-substrate-is-named.md) |
-| [`08-connectivity.md`](08-connectivity.md) | One context in full — overlay, resolution, exposure, filtering, certificates | [ADR 0049](../../02-DECISIONS/0049-a-route-is-a-grant.md), [0050](../../02-DECISIONS/0050-reachability-is-a-property-of-the-address.md), [0051](../../02-DECISIONS/0051-the-enrolment-token-carries-the-mesh.md) |
+| [`08-connectivity.md`](08-connectivity.md) | One context in full — overlay, resolution, exposure, filtering, certificates | [ADR 0049](../../02-DECISIONS/0049-a-route-is-a-grant.md), [0050](../../02-DECISIONS/0050-reachability-is-a-property-of-the-address.md), [0051](../../02-DECISIONS/0051-the-enrolment-token-carries-the-mesh.md), [0055](../../02-DECISIONS/0055-the-control-plane-is-the-node-coordinating-contexts.md) |
 
 ## Not yet written
 
-- **The remaining contexts.** [ADR 0015](../../02-DECISIONS/0015-mesh-brokers-nodes-host-agents-think.md)
-  decides the decomposition; `connectivity` is the first written in full
-  ([`08`](08-connectivity.md)) and the others do not exist yet. The work breakdown says in what
-  order they are needed.
+- **The remaining six contexts.**
+  [ADR 0055](../../02-DECISIONS/0055-the-control-plane-is-the-node-coordinating-contexts.md)
+  settles the list at seven; `connectivity` is the first written in full
+  ([`08`](08-connectivity.md)) and the other six do not exist yet. The work breakdown says in
+  what order they are needed.
 - ~~**Domain grouping outside the core.**~~ **Not needed.**
   [ADR 0017](../../02-DECISIONS/0017-modules-outside-the-core-are-grouped-by-domain.md) is
   superseded by [ADR 0044](../../02-DECISIONS/0044-a-module-declares-presence-instantiation-and-exclusion.md):