Full worked-example coverage across check types and inspectors, gated by a completeness test

[abegong]

Summary

PR #82 (under #30) embeds inline test-based worked examples into the pages that own each feature, but coverage is partial: 11 examples exist, 7 routed onto reference pages, covering only a handful of the ~30 check types and 2 of the inspectors. Drive this to full coverage — a worked example for every check type and inspector — and gate completeness with a test so new types can't land undocumented.

Current state

• internal/examples/examples.go holds the registry; TestExamples golden-gates each example's rendered output; cmd/gendocs (examplesByPage) routes feature examples onto their reference page.
• Covered today: object_field_type, object_required_field, markdown_title_matches_h1, text_forbids, the document_shape and object_fields inspectors, plus the structured-object family happy path. Every other check type and inspector has no worked example.

Task

• Backfill a worked example for every remaining check type (the families under internal/checks/) and every inspector under internal/inspect/, each minimal and on-topic for its host page.
• Add a completeness test that fails when a checks.Descriptor or inspect.Descriptor has no associated worked example, with an explicit, commented allowlist for any intentional exemptions — so a gap is a deliberate decision, not an oversight.
• Follow the corpus house style from Add worked examples registry with test gating and doc generation #82 (data-first input; inline checks where they fit; schema only where the example is specifically about schemas).

Why

A worked, tested example on every rule's reference page makes the docs both complete and self-verifying: the same run that documents a check gates its behavior. The completeness test turns "we should add an example here" from a good intention into a CI requirement, the same way docs-gen-check already gates drift.

Related

• Implement build-docs-from-tests #30 (build-docs-from-tests) — parent.
• Inline examples on check types (pass/fail samples that document and self-test a rule) #52 (inline pass/fail examples on check types) — a per-rule pass/fail mechanism that could converge with or complement these worked examples; decide the relationship.
• Review all tests and define an opinionated testing approach #38 (define an opinionated testing approach) — the completeness test should fit that standard.