[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/HomeView+Data.swift

@@ -177,7 +177,7 @@ extension HomeView {
 
 extension StoreSummary {
     /// Maps the public-locator DTO onto the same model HomeView already
-    /// renders — distance/positiveReviews don't exist in that response.
+    /// renders — positiveReviews doesn't exist in that response.
     init(publicItem: PublicStoreListItem) {
         self.id = publicItem.id
         self.name = publicItem.name ?? "Loja"
@@ -189,7 +189,10 @@ extension StoreSummary {
         self.positiveReviews = nil
         self.deliveryTime = publicItem.deliveryTime
         self.deliveryFee = publicItem.deliveryFee
-        self.distance = nil
+        // The contract uses `0` for "no distance available"; normalize it to
+        // nil here so every downstream consumer (card label, max-distance
+        // filter) sees one representation of "unknown".
+        self.distance = (publicItem.distance ?? 0) > 0 ? publicItem.distance : nil
         self.isOpen = publicItem.isOpen
         self.statusLabel = publicItem.statusLabel
     }