feat: docs reference generates a human command reference under docs/reference/ from the command records, one page per group plus exit codes and gates; toc never lands inside another generated region (#188)

Files changed:
- CHANGES.md
- README.md
- VERSION
- docs/reference/README.md
- docs/reference/commands/README.md
- docs/reference/commands/catalog-and-log.md
- docs/reference/commands/content-migrations.md
- docs/reference/commands/distribution-and-versioning.md
- docs/reference/commands/finding-and-checking.md
- docs/reference/commands/git.md
- docs/reference/commands/guideline-export.md
- docs/reference/commands/instance-health.md
- docs/reference/commands/links-and-citations.md
- docs/reference/commands/pages.md
- docs/reference/commands/provenance.md
- docs/reference/commands/raw-material-and-uploads.md
- docs/reference/commands/telemetry.md
- docs/reference/commands/types-instructions-and-docs.md
- docs/reference/commands/workshop-runs-and-session-budget.md
- docs/reference/exit-codes.md
- instructions/dev/doc-pull-through.md
- tools/CONTRACT.md
- tools/README.md
- tools/chemenu/cli.py
- tools/chemenu/cli_contract.py
- tools/chemenu/commands/docs_verify.py
- tools/chemenu/reference_doc.py
- tools/chemenu/tests/test_reference_doc.py
- tools/chemenu/toc.py

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

instructions/dev/doc-pull-through.md

@@ -33,7 +33,7 @@ touched; a row that does not apply needs no action.
 
    | Touched surface | Document(s) that make a claim about it |
    |---|---|
-   | A `wikitool` command's behaviour, flags, or interface | Its `cli_contract.CommandRecord` (name, synopsis, properties, exit status, retry policy - `tools/chemenu/cli_contract.py`), then `wikitool docs contract --apply` to regenerate its copy in [tools/CONTRACT.md](../../tools/CONTRACT.md) |
+   | A `wikitool` command's behaviour, flags, or interface | Its `cli_contract.CommandRecord` (name, synopsis, properties, exit status, retry policy - `tools/chemenu/cli_contract.py`), then `wikitool docs contract --apply` to regenerate its copy in [tools/CONTRACT.md](../../tools/CONTRACT.md) and `wikitool docs reference --apply` for the human reference under `docs/reference/` (a new group in `cli_contract.GROUPS` first needs its page there, with a title, a one-sentence head and the marker pair) |
    | A stage's authoring rules (`raw/`, `kb/`, `types/`, `reports/`, `work/`, `tools/`, `instructions/`) | The touched `<stage>/CONTRACT.md` |
    | A rule, gate, or invariant `AGENTS.md` itself states | The relevant `AGENTS.md` section (Invariants, Gates, File naming, Routing, ...) |
    | A workflow, stage, or command a human operates by hand | Whichever of `README.md`, `EVALS.md`, `tools/README.md`, `INSTALL.md`, `INSTALL-MCP.md` or the pages under `docs/tutorials/`, `docs/how-to/` and `docs/reference/` names it - AGENTS.md § File naming says which document is for which reader. A new page goes into the area its kind of documentation belongs to; that area's `README.md` says which |