Shipping policy

[COPY NEEDED: Full shipping policy. Dean to supply final wording — see BRIEF.md section 5.8.]

Approved copy already confirmed in BRIEF.md to build this around:

• “Free UK delivery” (announcement bar / trust strip, sections 6.1, 6.4, 7)

Still needed: dispatch/delivery timeframes, carrier, whether delivery is UK-only or includes Northern Ireland/Ireland/international, and how the Nutribl dropship fulfilment affects timing (see open item in BRIEF.md section 10: Nutribl integration not yet confirmed).