docs(skills): extract house recipes as Claude Code skills for SSP templating

8 template-generic skills in .claude/skills/ (new-feature, new-context,
value-object, form-machine, bff-endpoint, mutation-command, ui-component,
new-ssp), condensed from CLAUDE.md/ARCHITECTURE/fp-tea/ADRs and pointing at
this repo's worked examples. CLAUDE.md gains a pointer.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -161,6 +161,10 @@ Domain first (types + pure rules + spec, no Angular) → infrastructure (adapter
 union + pure reduce) → UI last (compose `shared/ui` atoms, wrap async in `<app-async>`,
 dispatch messages). Worked example: the intake wizard (`herregistratie/`).
 
+The recipes are also invocable skills in `.claude/skills/`: `new-feature`,
+`new-context`, `value-object`, `form-machine`, `bff-endpoint`, `mutation-command`,
+`ui-component`, `new-ssp` (bootstrap a new portal from this template).
+
 ## Out of scope (POC, don't build unprompted)
 
 Real auth/DigiD, NgRx, licensed RO/Rijks fonts + logo (system-font stack; text wordmark),