Consolidate: 65 decision records to 23

Every remaining cluster merged. Each was one design that had been split across
several records because it was worked out over days rather than at once.

  the node host          8 -> 1    applies not decides, depends on nothing,
                                   per operating system, root service, the
                                   launcher, episodic, what a declaration is,
                                   actions from the bundle only
  a node and how it joins 4 -> 1   what a node is, joining, the link as
                                   security boundary, the enrolment token
  modules and the graph   7 -> 1   everything is a module, no domain modules,
                                   three edges, provisioning, the core library
  substrate and control   6 -> 1   the test, seven contexts, one control plane,
    plane                          the authority is not a database, the named
                                   products, the pinned bundle
  connectivity            3 -> 1   a route is a grant, reachability declared,
                                   filter rules
  delivery                5 -> 1   reconciliation not a pipeline, artifacts,
                                   the three silos, a failed step, the verdict
  the lab                 5 -> 1   (earlier)
  how this repository     10 -> 1  (earlier)
    works

Nothing was dropped. Each consolidated record carries the reasoning of the ones
it absorbs -- the measurements, the incidents, the alternatives rejected --
because that reasoning is the only reason to keep a record at all. What is gone
is the fragmentation: eight files to read to understand tier 0, when tier 0 is
one component.

The four superseded records went too. They existed to point at their
successors, and the successors now contain what they said.

The checker made this safe. Each merge left dangling links -- 38 files after
the host merge alone -- and it named every one. Nothing was found by reading,
and a manual pass would certainly have missed some, including references inside
AGENTS.md which every session loads.

00-META/checks/README.md

@@ -31,7 +31,7 @@ indistinguishable from one that cannot.
   having it.
 - **`03-DESIGN/00-as-is/` may rest on a superseded record.** It describes what runs, and what
   runs was built under whatever was decided at the time
-  ([ADR 0056](../../02-DECISIONS/0056-the-authority-is-the-control-plane-not-a-database.md):
+  ([ADR 0048](../../02-DECISIONS/0048-the-substrate-and-the-control-plane.md):
   *as-is describing a superseded decision is exactly what as-is is for*).
 - **Whether a citation's prose is still true.** Only whether the record it points at is live.
   A document can cite an accepted record and describe it wrongly, and nothing here notices.