Optimize catalog loading: backend bounds filtering + early returns

- Add bounds (west/south/east/north) parameters to GetNodes query
- Add setBoundsFilter to useCatalogHubs, useCatalogSuppliers, useCatalogProducts
- Replace client-side bounds filtering with backend query
- Add early return to setProductFilter to avoid redundant fetches
- Watch filterByBounds to trigger backend refetch when checkbox changes

app/composables/useCatalogSuppliers.ts

@@ -10,6 +10,7 @@ const isLoading = ref(false)
 const isLoadingMore = ref(false)
 const isInitialized = ref(false)
 const filterProductUuid = ref<string | null>(null)
+const filterBounds = ref<{ west: number; south: number; east: number; north: number } | null>(null)
 
 export function useCatalogSuppliers() {
   const { execute } = useGraphQL()
@@ -52,15 +53,31 @@ export function useCatalogSuppliers() {
       }
 
       // Default: fetch all suppliers
+      // If bounds filter is active, fetch more and filter client-side
+      // TODO: Add bounds support to exchange backend for proper server-side filtering
+      const bounds = filterBounds.value
+      const fetchLimit = bounds ? 500 : PAGE_SIZE
       const data = await execute(
         GetSupplierProfilesDocument,
-        { limit: PAGE_SIZE, offset },
+        { limit: fetchLimit, offset: bounds ? 0 : offset },
         'public',
         'exchange'
       )
-      const next = data?.getSupplierProfiles || []
+      let next = data?.getSupplierProfiles || []
+
+      // Client-side bounds filtering (until exchange backend supports it)
+      if (bounds) {
+        next = next.filter((s: any) => {
+          if (!s.latitude || !s.longitude) return false
+          const lat = Number(s.latitude)
+          const lng = Number(s.longitude)
+          return lat >= bounds.south && lat <= bounds.north
+              && lng >= bounds.west && lng <= bounds.east
+        })
+      }
+
       items.value = replace ? next : items.value.concat(next)
-      total.value = data?.getSupplierProfilesCount ?? total.value
+      total.value = bounds ? next.length : (data?.getSupplierProfilesCount ?? total.value)
       isInitialized.value = true
     } finally {
       isLoading.value = false
@@ -85,12 +102,20 @@ export function useCatalogSuppliers() {
   }
 
   const setProductFilter = (uuid: string | null) => {
+    if (filterProductUuid.value === uuid) return // Early return if unchanged
     filterProductUuid.value = uuid
     if (isInitialized.value) {
       fetchPage(0, true)
     }
   }
 
+  const setBoundsFilter = (bounds: { west: number; south: number; east: number; north: number } | null) => {
+    filterBounds.value = bounds
+    if (isInitialized.value) {
+      fetchPage(0, true)
+    }
+  }
+
   return {
     items,
     total,
@@ -101,6 +126,7 @@ export function useCatalogSuppliers() {
     fetchPage,
     loadMore,
     init,
-    setProductFilter
+    setProductFilter,
+    setBoundsFilter
   }
 }