feat!: docs/ sorted into tutorials, how-to, reference, explanation plus unshipped docs/dev/; explanation pages and developer guide moved, human docs English (#187)

The seven explanation pages move to docs/explanation/ without a stub, DEVELOPMENT.md becomes docs/dev/development.md (translated to English), dist export leaves docs/dev/ out, docs verify rejects a file outside the five areas, and AGENTS.md states that the stack's human documentation is English. Required migration 9.0.0-docs-diataxis rewrites the old path in an instance's own kb/CONVENTIONS.md.

Files changed:
- .wikitool-kb.json
- AGENTS.md
- CHANGES.md
- CLAUDE.md
- DEVELOPMENT.md
- INSTALL.md
- README.md
- VERSION
- docs/dev/development.md
- docs/explanation/README.md
- docs/explanation/knowledge-and-commitment.md
- docs/explanation/language-boundaries.md
- docs/explanation/model-and-effort-selection.md
- docs/explanation/ownership-and-templates.md
- docs/explanation/pipeline-rationale.md
- docs/explanation/version-model.md
- docs/explanation/why-gates-are-code.md
- docs/how-to/README.md
- docs/knowledge-and-commitment.md
- docs/language-boundaries.md
- docs/model-and-effort-selection.md
- docs/ownership-and-templates.md
- docs/pipeline-rationale.md
- docs/reference/README.md
- docs/tutorials/README.md
- docs/version-model.md
- docs/why-gates-are-code.md
- instructions/CONTRACT.md
- instructions/dev/dev-setup.md
- instructions/dev/doc-pull-through.md
- instructions/dev/stack-close/SKILL.md
- instructions/dev/stack-mode.md
- instructions/gtd-weekly-review/SKILL.md
- instructions/ingest-queue.md
- instructions/migrations/6.0.0-type-guidance-split.md
- instructions/migrations/9.0.0-docs-diataxis.md
- instructions/upgrade-instance.md
- kb/CONVENTIONS.md
- kb/CONVENTIONS.md.template
- tools/CONTRACT.md
- tools/chemenu/commands/dist_cmd.py
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/commands/new_page.py
- tools/chemenu/commands/task_cmd.py
- tools/chemenu/tasks/protocol.py
- tools/chemenu/tests/test_dist_cmd.py
- tools/chemenu/tests/test_docs_verify.py
- tools/chemenu/tests/test_git_publish.py
- tools/chemenu/tests/test_toc.py
- types/type-guidance.md

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2

instructions/upgrade-instance.md

@@ -209,7 +209,10 @@ a further checkout of this one ([bootstrap.md](bootstrap.md)).
    and filled is never touched. The `.template` files stay where they are - they are the source for the next upgrade's
    comparison. Any other failure is read against step 2's **Breaking Change:** line: if the
    release predicted it, the notes also say what fixes it; if it did not, stop and report it
-   rather than improvising.
+   rather than improvising. Where the fix they name is a required migration document - a
+   machinery-side file this instance owns, such as `kb/CONVENTIONS.md`, still pointing at a
+   path the release moved - leave the failure standing here: step 12 runs that document, and
+   step 13's `docs verify` is where it has to be gone.
 
 10. **Publish the machinery swap.** A release swap is far above the Mass-Update Gate's threshold,
     so expect exit 42. That is not an error and not yours to clear: reproduce the file breakdown
@@ -254,6 +257,7 @@ a further checkout of this one ([bootstrap.md](bootstrap.md)).
     ```bash
     tools/wikitool migrate verify --from <pre-swap commit>
     tools/wikitool lint
+    tools/wikitool docs verify
     ```
 
     `migrate verify` is the only check that sees a page which lost a citation, a wikilink or a