stack: TOC-Scope auf types/ und docs/, Sprachregeln nach AGENTS.md zentralisiert, alle Templates auf Control-Plane-Sprache, --breaking akkumuliert (schliesst #99)

Files changed:
- AGENTS.md
- CHANGES.md
- ENVIRONMENT.md.template
- SOUL.md
- SOUL.md.template
- USER.md.template
- VERSION
- docs/ownership-and-templates.md
- docs/version-model.md
- instructions/CONTRACT.md
- instructions/dev/doc-pull-through.md
- instructions/dev/stack-close/SKILL.md
- instructions/dev/stack-dev/SKILL.md
- instructions/dev/version-parts.md
- instructions/setup-instance.md
- kb/CONVENTIONS.md
- kb/CONVENTIONS.md.template
- kb/concepts/COLLECTION.md
- kb/sources/COLLECTION.md
- tools/CONTRACT.md
- tools/chemenu/commands/types_cmd.py
- tools/chemenu/commands/version_cmd.py
- tools/chemenu/tests/test_toc.py
- tools/chemenu/tests/test_version_cmd.py
- tools/chemenu/toc.py
- tools/chemenu/version.py
- types/comparison.md
- types/concept.md
- types/entity.md
- types/lint-report.md
- types/source.md

instructions/dev/stack-close/SKILL.md

@@ -48,10 +48,12 @@ and a fresh subagent starts without the session's context).
 
 ## Steps
 
-1. **Offer the model switch back up, once, and keep working either way.**
+1. **Offer the model switch back up, once, and keep working either way.** A model of the
+   message, not a script to quote: say it in the instance's KB language, per `AGENTS.md`
+   § File naming.
 
-   > Ab hier greift kein maschineller Check mehr - Issue-Body, `docs/`-Veralterung und
-   > Changelog-Prosa prüft nichts. Wenn du zurück auf Opus willst, ist jetzt der Moment.
+   > From here on no mechanical check applies - nothing verifies the issue body, `docs/`
+   > staleness, or the changelog prose. If you want to switch back to Opus, now is the moment.
 
    **Never block on the answer.** The change is already published; a session that stops here
    leaves exactly the state this skill exists to prevent.
@@ -86,6 +88,11 @@ and a fresh subagent starts without the session's context).
    behaviour one of these documents describes, update it now; if none did, say so rather than
    leaving the question unasked.
 
+   **If that update moved a `##`/`###` heading, the file's table of contents is now stale** -
+   regenerate it with `tools/wikitool docs toc --apply`, never by editing the list. The region
+   is generated (AGENTS.md invariant 1), `docs verify` fails on stale exactly as on missing, and
+   a pull-through in this phase is a common way to move a heading without noticing.
+
    **A pull-through of its own needs its own bump.** This phase runs *after* `stack-dev` step 4
    has already bumped the version, and the documents it touches are frequently the ones CI's
    version gate watches - `types/`, `instructions/`, `tools/`, `AGENTS.md`, any