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

AGENTS.md

@@ -107,6 +107,25 @@ documents. What it may not carry is the same content twice - a README that resta
 contract is a second copy that drifts. `docs verify` enforces the specific case that already
 happened once: no README may hold a copy of the `wikitool` command table.
 
+**Two languages, and which is which.** Every file in the table above belongs to the stack and
+ships to instances that share none of this instance's language choices, so:
+
+1. **The control plane is written in English** - this file, `CLAUDE.md`, every `CONTRACT.md`,
+   everything under `instructions/`, and the type-specs for non-page artifacts. Quoted
+   vocabulary is not prose and stays as it is: a section name, a relationship label or a
+   translated term cited as evidence. What the *instance* owns goes the other way - `kb/` pages
+   and the page type-specs that shape them follow `kb/CONVENTIONS.md`, which is also where the
+   instance's own terminology material is reached from.
+2. **An agent speaks the instance's KB language**, whatever this file is written in. The value
+   lives in `kb/CONVENTIONS.md`'s `language:` and nowhere else; an instruction that models a
+   sentence for the user writes it in English like the rest of the control plane, and the agent
+   says it in that language.
+
+Nothing checks either mechanically - a stop-word scan would flag the quoted vocabulary above
+and miss a translated paragraph that reads cleanly. They are held up by whoever writes an
+instruction, which is why [instructions/CONTRACT.md](instructions/CONTRACT.md) § "Writing an
+instruction" names them at the step where that happens.
+
 **`docs/` carries no normative sentence.** It holds why the stack is built the way it is -
 background consulted in passing, not a rule to follow; anything that would bind belongs in a
 `CONTRACT.md` instead, which is what keeps invariant 8 intact here. It carries no frontmatter,