MIL-011 tasks 2 to 4: the default tools-ref is the current major

code-metrics.yml defaulted tools-ref to v1 and its guide said @v1, but
the workflow and its scripts exist only from v2.1.0. The default of the
five reusable workflows is now the current major, defined once in
MAJOR_TAG, and tests/test_tools_ref.py fails when a default differs from
it or names a tag without the script. Guides, README and wiki (en, da,
ms) call code-metrics.yml at @v2; ADR-0005, 0008, 0009 and 0010 carry
an amendment; RC-077 accepts the milestone's task 1 results.

Task: MIL-011#2

CHANGELOG.md

@@ -20,6 +20,19 @@ Each release lists its changes in these groups, in this order:
 
 ## [Unreleased]
 
+### Fixed
+
+- `code-metrics.yml` could not be called as documented. Its guide, header
+  comment and `tools-ref` default named `v1`, which has neither the workflow nor
+  `tools/code-metrics.sh`: a call at `@v1` created no run, and a call at `@v2`
+  with the defaults failed in "Validate the inputs" (exit 127). The default
+  `tools-ref` of `code-metrics.yml`, `quality-checks.yml`,
+  `quality-checks-cpp.yml`, `quality-checks-csharp.yml` and
+  `publish-wiki-pages.yml` is now the current major (`v2`), defined once in
+  `MAJOR_TAG`, and a test fails when a default differs from it or names a tag
+  without the script. The guides, README and wiki pages call
+  `code-metrics.yml` at `@v2`.
+
 ## [2.1.0] - 2026-10-14
 
 ### Added