Fix: Improve UX with empty state, miles, and metric labels

1. Show empty state by default on home page
   - Don't fetch or display schools until user searches
   - Show helpful message prompting users to search
   - Only fetch schools when search params are present

2. Change distance search to miles
   - Display 0.5, 1, and 2 mile options instead of km
   - Convert miles to km when sending to API (backend expects km)
   - Convert km back to miles for display in location banner
   - Maintains backend compatibility while improving UX

3. Fix metric labels in rankings dropdown
   - Backend returns 'name' and 'type' fields
   - Frontend expects 'label' and 'format' fields
   - Added transformation in fetchMetrics to map fields
   - Dropdown now shows proper labels like "RWM Combined %"
     instead of technical codes like "rwm_expected_pct"

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

nextjs-app/components/HomeView.tsx

@@ -46,7 +46,7 @@ export function HomeView({ initialSchools, filters }: HomeViewProps) {
         <div className={styles.locationBanner}>
           <span className={styles.locationIcon}>📍</span>
           <span>
-            Showing schools within {initialSchools.location_info.radius}km of{' '}
+            Showing schools within {(initialSchools.location_info.radius / 1.60934).toFixed(1)} miles of{' '}
             <strong>{initialSchools.location_info.postcode}</strong>
           </span>
         </div>
@@ -74,14 +74,22 @@ export function HomeView({ initialSchools, filters }: HomeViewProps) {
 
         {initialSchools.schools.length === 0 ? (
           <EmptyState
-            title="No schools found"
-            message="Try adjusting your search criteria or filters to find schools."
-            action={{
-              label: 'Clear Filters',
-              onClick: () => {
-                window.location.href = '/';
-              },
-            }}
+            title={hasSearch ? "No schools found" : "Search for Schools"}
+            message={
+              hasSearch
+                ? "Try adjusting your search criteria or filters to find schools."
+                : "Use the search above to find schools by name or search by location to discover schools near a postcode."
+            }
+            action={
+              hasSearch
+                ? {
+                    label: 'Clear Filters',
+                    onClick: () => {
+                      window.location.href = '/';
+                    },
+                  }
+                : undefined
+            }
           />
         ) : (
           <>