docs(11.1): record the docs update rule and the wristband default todo

- CLAUDE.md: API, config-key and CLI changes update the affected docs
  pages; the docs checkers are named; config-key checking is deferred
- todo: wristband's default resource URL and comments name a consuming
  application

CLAUDE.md

@@ -29,7 +29,9 @@ These rules apply to every GSD phase in this project and override defaults:
 - Any change to a package under `modules/` that touches its exported API, config keys, CLI commands or dependencies must update that module's `README.md` in the same change (the same commit or PR).
 - A new module ships with a `README.md` that follows the standard structure: H1 name, one-sentence summary, import line, then Overview, Features, Usage, API reference, the optional Configuration and CLI commands sections, Dependencies and Testing. It also gets a row in the root `README.md` modules table, whose purpose text reuses the summary sentence.
 - Framework READMEs never name a consuming application. Say "the application" or "host application", and use neutral example names such as `blog` or `acme`.
-- Every identifier named in a README must exist in the package; check it with `go doc ./modules/<name> <Identifier>`.
+- Every identifier named in a README or a docs page must exist in the package. The docs checker verifies this automatically; `go doc ./modules/<name> <Identifier>` remains the manual check.
+- A change to a module's exported API, config keys or CLI commands also updates the affected pages under `docs/` in the same change. `go test ./cmd/summer -run TestDocsTree` and `summer docs:build --check` check identifiers, internal links and anchors, `src=` snippets, command names and consuming-application names across `docs/` and every module README.
+- Config keys named in README or docs pages are not checked automatically yet (deferred in Phase 11.1); review them by hand.
 
 <!-- GSD:project-start source:PROJECT.md -->
 ## Project