feat(FoodTruckScreen): replace vertical overlay list with horizontal scroll strip

[roncodes]

Summary

Replaces the old vertical list of food trucks in FoodTruckScreen.tsx with a horizontally scrollable strip that lives inside the existing top overlay panel, directly beneath the "Your Zone" row — exactly where the original list was.

Each item in the strip is a small chip: the vehicle avatar image sits directly on the panel surface with no background fill, and the truck's display name appears below it. The strip scrolls horizontally so the panel height stays fixed regardless of how many trucks are in the fleet, solving the core scalability problem.

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What changed

src/screens/FoodTruckScreen.tsx

Panel structure (the horizontal scroll is inside the panel, not at the bottom of the screen):

YStack bg='$background' borderRadius='$5'   ← existing panel
  ├── XStack  (info banner row)
  ├── Pressable > XStack  (zone row)
  └── FlatList horizontal  ← NEW: replaces the old vertical list
        └── renderFoodTruckChip()
              ├── Image (avatar, 44×44, no background)
              └── Text  (plate number / name)

Avatar rendering fix:
The serialized vehicle object exposes avatar_url as a top-level property (consistent with how VehicleMarker accesses it via vehicle.getAttribute('avatar_url')). The previous version used FastImage which introduced an unnecessary dependency. This version uses React Native's built-in Image component with a conditional source — { uri: vehicle.avatar_url } when present, falling back to the bundled assets/images/vehicles/light_commercial_van.png.

Chip design:

• Width: 72px, no background fill on the image
• Image: 44×44, resizeMode='contain'
• Label: fontSize={11}, fontWeight='500', max 2 lines, centred
• Pressed opacity: 0.65 for tactile feedback
• marginRight: 12 between chips, last chip has no trailing margin

Zone row divider:
borderBottomWidth on the zone row is now conditional — 1 when trucks are present (so the divider appears between the zone row and the scroll strip), 0 when the list is empty (clean bottom edge on the panel).

Removed:

• Bottom absolute overlay View and all associated useSafeTabBarHeight / useSafeAreaInsets positioning logic
• FastImage import
• useSafeTabBarHeight and useSafeAreaInsets hooks

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Testing Checklist

• Horizontal strip renders inside the top panel, below the zone row
• Strip is not visible at the bottom of the screen
• Vehicle avatar image renders correctly (no background fill on image)
• Fallback van image renders when avatar_url is null/empty
• Truck name appears below the icon
• Tapping a chip animates map to truck location and opens Catalog
• Panel height stays fixed as more trucks are added (horizontal scroll)
• Zone row shows divider only when trucks are present
• Dark mode and light mode both render correctly