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/brief/ui/letter-composer/letter-composer.stories.ts

@@ -181,7 +181,7 @@ export const Sent: Story = {
     }),
 };
 
-/** Approver's "Toon wijzigingen" (WP-27): a resubmitted letter with blocks changed,
+/** Approver's "Toon wijzigingen": a resubmitted letter with blocks changed,
     added and removed since the last rejection. */
 export const RejectionDiff: Story = {
   render: () =>