refactor: strip WP-/RB- ticket refs from apps and libs (RD-18)

204 WP-NN/RB-NN comments named a closed ticket instead of the code they
sit next to. git blame already records history and stays correct when
code moves; the comment does not. This sweep removes the reference and
keeps the sentence, across 95 files in apps/ and libs/ plus the
behaviour-spec generator's header text.

Eleven references stay: five story files justify an a11y disable per
the README's rule, and one line in a11y.mdx documents that convention.
Two sentences needed a rewrite, not a deletion, so the reference's
meaning survives its removal. behaviour-spec.mdx is regenerated, not
hand-edited.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/ssp/src/app/showcase/highlight-ts.ts

@@ -1,5 +1,5 @@
 /**
- * Tiny, dependency-free TS highlighter for the teaching showcase (WP-39). Escapes HTML,
+ * Tiny, dependency-free TS highlighter for the teaching showcase. Escapes HTML,
  * then wraps line-comments, strings, and a fixed keyword set in `.c`/`.s`/`.k` spans (the
  * classes `concepts.page` styles). Deliberately naive — good enough for the short, curated
  * snippets shown here; not a real tokenizer. Input is always our OWN source (extracted by