[BUG] Shipping zones: only first zone published, product costs override to zero

[BenGWeeks]

Description

There seems to be unclear behavior with shipping zones in the Nostr Market extension. Multiple issues observed:

Issue 1: Only first shipping zone is published to relays

When multiple shipping zones are configured for a stall, only the first zone appears in the published kind 30017 (stall) event on Nostr relays.

Configured zones in LNbits:

• UK (cost: 15 GBP, countries: United Kingdom)
• Digital Only (cost: 0 GBP, countries: All)
• Worldwide

What appears on relays:

"shipping": [
  {"id": "b9MvGgC4XsNYRLy6vkFzPo", "name": "UK", "cost": 15, "countries": ["United Kingdom**"]}
]

Only the UK zone is published, the other zones are missing. Using "Republish to Nostr" does not resolve this.

Issue 2: Only "UK" zone appears under each product

When editing products, only the "UK" shipping zone is available/visible, not the other configured zones.

Issue 3: Product shipping cost always overrides to zero

The shipping cost for products always seems to override to zero, requiring manual correction back to the stall's default value each time.

Steps to Reproduce

1. Create a stall with currency GBP
2. Add multiple shipping zones via ZONES button (UK, Digital Only, Worldwide)
3. Save the stall
4. Click "Republish to Nostr"
5. Query relays for the stall event (kind 30017) - only first zone appears
6. Edit a product - only UK zone visible, cost defaults to 0

Expected Behavior

• All configured shipping zones should be published to relays
• All zones should be available when editing products
• Product shipping costs should default to the stall zone's cost, not zero

Environment

• Nostr Market extension: v1.0.1
• Nostr Client extension: v1.0.1
• LNbits v1.2.1

[BenGWeeks]

This may have been a UI thing. Need to retest this now that Shipping Zones are populated into a table.