[agoldis]

Fixes ENG-412: checkout rejected UK postcodes typed with a space.

Cause: the GB format in shipping.mjs (/^[A-Z]{1,2}\d[A-Z\d]?\d[A-Z]{2}$/) has no space, so POST /api/shipping-rates with SW1A 1AA returned 422 invalid_postcode, and the shipping step showed "Sorry, we can't deliver to this address."

Fix: quoteShipping removes whitespace and upper-cases the postcode before checking it. SW1A 1AA and sw1a1aa now get delivery options; a partial postcode such as SW1A is still rejected.

Verified:

• curl against the local shop: SW1A 1AA returns both GB rates, SW1A returns 422.
• Browser run of the support session's steps: delivery options show, total £46.95, "Continue to payment" enabled. Screenshots and session links are in the comment below.

🤖 Generated with Claude Code

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[agoldis]

Before and after for SW1A 1AA on the shipping step.

• Before (support session, failed): https://s.crts.sh/ai/FrRi7bf2xxA3Fagk. POST /api/shipping-rates returns 422 invalid_postcode, "Sorry, we can't deliver to this address.", Continue to payment disabled.
• After (this branch, passed): https://s.crts.sh/ai/OgUWMzmtf4yHsMmV. Royal Mail Tracked 48 and DPD Next Day shown, total £46.95, Continue to payment enabled, no console errors or failed requests.

Screenshots attached: cant-deliver-sw1a.png (before), delivery-options-sw1a.png (after).