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

README.md

@@ -53,10 +53,26 @@ Two starting points, depending on what you're doing:
 <!-- dist:strip-start -->
 - **Working on the stack itself.** A clone of this repository is a development checkout, with
   the demo corpus described below; it is never an instance. Setting it up, and `dist export` as
-  the build and test tool it is, are in `DEVELOPMENT.md` (for you) and
+  the build and test tool it is, are in `docs/dev/development.md` (for you) and
   `instructions/dev/dev-setup.md` (for the agent).
 <!-- dist:strip-end -->
 
+## Documentation
+
+The human documentation lives under `docs/`, sorted by what you want from it:
+
+- [docs/tutorials/](docs/tutorials/README.md) - learning: a guided first walk through an
+  instance. Installation is still [INSTALL.md](INSTALL.md).
+- [docs/how-to/](docs/how-to/README.md) - doing: one task per page, for the operator of an
+  instance.
+- [docs/reference/](docs/reference/README.md) - looking up: commands, exit codes, skills, page
+  types. The command reference is [tools/CONTRACT.md](tools/CONTRACT.md).
+- [docs/explanation/](docs/explanation/README.md) - understanding: why the stack is built the way
+  it is.
+
+The areas are filling up gradually; until a page exists there, the sections below still carry
+its material.
+
 ## Architecture
 
 ```
@@ -76,6 +92,7 @@ chemenu/
 │                       #   incoming/ is the one directory excluded the other way round
 ├── .github/hooks/      # Copilot CLI hooks - session tracing
 ├── .vibe/              # Mistral Vibe hooks + the repo's telemetry policy
+├── docs/               # Human documentation: tutorials/, how-to/, reference/, explanation/
 ├── instructions/       # CONTROL: everything an agent is told to do
 │   ├── CONTRACT.md     # Instruction vs. skill, publishing, writing standard
 │   ├── bootstrap.md    # Prepare a further checkout of an instance
@@ -155,7 +172,7 @@ chemenu/
 Dev-instance-only (see `tools/CONTRACT.md` for how it got here):
 
 ```
-├── DEVELOPMENT.md      # Human-readable: the release workflow (version bump/release/publish/CI)
+├── docs/dev/           # Human-readable: development environment and release workflow
 └── commonplace/        # Vendored, read-only knowledge base
 ```
 <!-- dist:strip-end -->
@@ -294,7 +311,7 @@ way `task new` opened it, or the way the weekly review proposes it for a
 `waiting_overdue`/`someday_stale` finding once you confirm.
 
 Why the split runs this way, rather than syncing the two:
-[docs/knowledge-and-commitment.md](docs/knowledge-and-commitment.md).
+[docs/explanation/knowledge-and-commitment.md](docs/explanation/knowledge-and-commitment.md).
 
 ## Entity Types