Every provider lived at /coach/<pubkey>/<id> regardless of craft (a barber got
a "coach" URL). New src/lib/labRoutes.ts maps craft kind → segment and builds
the canonical path; the router adds /lab/:craft/:pubkey/:identifier (the craft
segment is cosmetic — the page still resolves by pubkey + identifier) and keeps
/coach/... working for old links. All generated links updated: offer-form
redirects, Lab cards + "Your Lab profiles", cross-links, spot/event/admin links,
the CVM client URL, the share path, and the SPA clean-link shim.
