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/dev/stack-close/SKILL.md

@@ -23,7 +23,7 @@ phases this one ends; read it first when this session started cold.
 The phases around the checked middle of a work package have no mechanical guard at all -
 `pytest`, `docs verify`, `instructions verify` and CI cover the code and tests in between, and
 nothing covers a changelog entry's accuracy, a `docs/` page's staleness, or an issue body's final
-state (see `docs/model-and-effort-selection.md`). Asking the same session to notice it has
+state (see `docs/explanation/model-and-effort-selection.md`). Asking the same session to notice it has
 crossed into that unchecked stretch - as a prose break inside one long skill - failed twice in a
 row on this stack (Gitea #42, then #30): both times the session knew the rule and skipped past
 it anyway, because nothing in the moment forced the question. The first split (Gitea #47) moved
@@ -71,7 +71,7 @@ always will.
    naming) - the same is true of `tools/CONTRACT.md`'s generated command records and any touched
    `<stage>/CONTRACT.md`, whose prose `docs verify` checks only for presence and record
    membership, never for what a field or a section actually says
-   (`instructions/dev/doc-pull-through.md`); of `README.md`/`INSTALL.md`/`DEVELOPMENT.md`
+   (`instructions/dev/doc-pull-through.md`); of `README.md`/`INSTALL.md`/`docs/`
    prose; and of a new instruction's own wording, which `instructions verify` checks structurally
    but never for what it claims. If the change this package shipped moved the reasoning or the
    behaviour one of these documents describes, update it now; if none did, say so rather than