[public-store-distance] Consume the public distance contract, stop labelling it as unavailable

Guest browsing showed 'Distância indisponível' on every store card and a
'--' tile on store detail, because the public locator response carries no
distance and StoreSummary.init(publicItem:) hardcoded nil.

Backend contract (docs/plans/public-store-distance-consumer.md): distance
is a number, never null, 0 means unavailable. Implemented app-side ahead of
the backend - every change is forward-compatible, and the part that removes
the broken label works with no backend at all.

- PublicStoreListItem / PublicStoreDetail: + distance (optional, so today's
  responses without the field still decode).
- StoreSummary.init(publicItem:): normalize the 0 sentinel to nil, so one
  representation of 'unknown' reaches the label and the max-distance filter.
- fetchStoreDetail: send state/city from GuestLocationStore by default -
  the server needs them to resolve the city centroid.
- formatDistance: empty string for nil/0/negative. It previously returned
  'Distância indisponível' for nil, and - found by the new test - '0 m' for
  0 and '-1000 m' for a negative.
- StoreCard: drop the distance segment and its '·' separator together,
  otherwise the row ended in a dangling separator.
- StoreDetailView: drop the DISTÂNCIA tile and its divider instead of '--'.

Also fixes the same label in the authenticated flow when the user declined
location and has no address coordinates.

Tests: PublicStoreDistanceTests (decode with/without the field, passthrough,
0 normalization) + the empty case in HomeViewFilteringTests.

PediFoods/Views/Main/StoreDetailView+Components.swift

@@ -109,8 +109,13 @@ extension StoreDetailView {
                 }
 
                 HStack(spacing: 0) {
-                    statItem(title: "DISTÂNCIA", value: distanceValueLabel)
-                    Divider().frame(height: 34)
+                    // No distance available: drop the tile and its divider
+                    // instead of showing a placeholder - see
+                    // docs/plans/public-store-distance-consumer.md.
+                    if hasStoreDistance {
+                        statItem(title: "DISTÂNCIA", value: distanceValueLabel)
+                        Divider().frame(height: 34)
+                    }
                     if let deliveryTime = info?.deliveryTime {
                         statItem(title: "TEMPO MIN.", value: deliveryTime+" min.")
                     } else {