feat(11.1-02): check links, commands, forbidden names and fence policy

- relative links and anchors resolve against the renderer's heading IDs
- summer and ./bin/<app> command names come from the real command
  constructors through docsite.Options.Commands; a nil set is a problem
- consuming-application names fail in page sources and built outputs
- go fences in docs/ pages need src=, callouts are NOTE, TIP or WARNING,
  docs/ headings are plain ASCII
- gate gains --claude and self-test plants for each new rule

internal/docsite/docsite.go

@@ -34,6 +34,9 @@ type Options struct {
 	Out string
 	// BaseURL overrides site.yaml base_url when non-empty.
 	BaseURL string
+	// Commands is the set of summer and application command names pages
+	// may show. Check and Build report a problem when it is nil.
+	Commands *Commands
 }
 
 // Problem is one finding in the docs source, printed as
@@ -230,7 +233,9 @@ func writeOutputs(out string, files map[string][]byte) error {
 }
 
 // checkContent runs the accuracy checkers over every page and the root
-// README.md: module identifiers named in code spans.
+// README.md: module identifiers, links and anchors, command names,
+// consuming-application names in the sources, and the fence, callout and
+// heading policy.
 func (s *site) checkContent() ([]Problem, error) {
 	docs, err := s.parseDocs()
 	if err != nil {
@@ -241,6 +246,18 @@ func (s *site) checkContent() ([]Problem, error) {
 		return nil, err
 	}
 	problems = append(problems, s.checkIdentifiers(idx, docs)...)
+	problems = append(problems, s.checkLinks(docs)...)
+	cp, err := s.checkCommands(docs)
+	if err != nil {
+		return nil, err
+	}
+	problems = append(problems, cp...)
+	fp, err := s.checkForbiddenSources()
+	if err != nil {
+		return nil, err
+	}
+	problems = append(problems, fp...)
+	problems = append(problems, s.checkPolicy(docs)...)
 	return problems, nil
 }