Renumber the records 1 to 23

The consolidation left a sparse sequence -- 1, 4, 6, 7, 9, 10, 12, 15, 16, 18,
19, 25, 34, 35, 36, 37, 40, 42, 44, 45, 48, 49, 58 -- where the gaps were only
the archaeology of what used to be there.

Renumbered contiguously. Renames run in ascending order, so every target number
is already free and no two files ever collide.

The reference rewrite is one simultaneous pass rather than a sequence of
replacements. Numbers moved into slots other numbers were vacating -- the node
host went 37 to 16 while the lab went 16 to 9 -- so replacing one at a time
would have cascaded and silently pointed things at the wrong record.

Seven plain-text references survived the merges as prose rather than links,
naming records that no longer existed: the enrolment token, the link boundary,
what a declaration is, reachability, the repository structure. Each mapped to
the consolidated record that now holds it.

Verified rather than assumed: every [ADR NNNN](path) link now has matching text
and target, checked across the whole repository, and the checker passes.

Frontmatter `consolidates:` lists dropped -- they named records that are gone,
and each consolidated record already says in prose what it absorbed.

00-META/checks/README.md

@@ -20,7 +20,7 @@ indistinguishable from one that cannot.
 | `links` | every relative link resolves | — (run ad hoc during authoring; now permanent) |
 | `rests-on` | `decisions:` and `extends:` name records that exist and are **accepted** | the class behind both incidents |
 | `live-citation` | a governing document citing a **superseded** record names its replacement in the same paragraph | `01-to-be/README.md` citing ADR 0017 as live guidance |
-| `supersession` | if A says it was superseded by B, B says it supersedes A | ADR 0018 never declared that it superseded 0011 |
+| `supersession` | if A says it was superseded by B, B says it supersedes A | ADR 0010 never declared that it superseded 0011 |
 | `numbering` | the number in the filename is the number in the heading | — |
 
 ## What is deliberately not checked
@@ -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 - **`03-DESIGN/00-as-is/` may rest on a superseded record.** It describes what runs, and what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 0048](../../02-DECISIONS/0048-the-substrate-and-the-control-plane.md):
+  ([ADR 0021](../../02-DECISIONS/0021-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   *as-is describing a superseded decision is exactly what as-is is for*).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.