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

types/type-guidance.md

@@ -55,7 +55,7 @@ that file's own `guidance:` frontmatter field.
 Relevant Notes:
 
 - Ships verbatim with every distribution; the type-spec it documents ships only as a `.template`
-  where `root: kb` - see `docs/ownership-and-templates.md` § "Where the file boundary used to
+  where `root: kb` - see `docs/explanation/ownership-and-templates.md` § "Where the file boundary used to
   strain"
 - No `## Template` section here: a guidance file's body is prose an author reads, not a body
   structure `wikitool new` would scaffold. `type-guidance` declares no `base_dir:` for the same