fix(search): correct radius units and distance display for postcode search

FilterBar was sending radius in km (e.g. 1.6) but the backend expects miles,
causing the "Showing schools within X miles" banner to display the wrong value.
Change option values to miles (0.5, 1, 3, 5, 10) and default from 1.6 to 1.

school.distance from the API is already in miles (backend haversine uses
R=3959). SchoolRow was dividing by 1609.34 giving 0.0 mi; CompactSchoolItem
was dividing by 1.60934. Both now display school.distance directly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

nextjs-app/components/FilterBar.tsx

@@ -20,7 +20,7 @@ export function FilterBar({ filters, isHero }: FilterBarProps) {
 
   const currentSearch = searchParams.get('search') || '';
   const currentPostcode = searchParams.get('postcode') || '';
-  const currentRadius = searchParams.get('radius') || '1.6';
+  const currentRadius = searchParams.get('radius') || '1';
   const initialOmniValue = currentPostcode || currentSearch;
 
   const [omniValue, setOmniValue] = useState(initialOmniValue);
@@ -69,7 +69,7 @@ export function FilterBar({ filters, isHero }: FilterBarProps) {
     }
 
     if (isValidPostcode(omniValue)) {
-      updateURL({ postcode: omniValue.trim().toUpperCase(), radius: currentRadius || '1.6', search: '' });
+      updateURL({ postcode: omniValue.trim().toUpperCase(), radius: currentRadius || '1', search: '' });
     } else {
       updateURL({ search: omniValue.trim(), postcode: '', radius: '' });
     }
@@ -113,11 +113,11 @@ export function FilterBar({ filters, isHero }: FilterBarProps) {
               className={styles.radiusSelect}
               disabled={isPending}
             >
-              <option value="0.8">0.5 miles</option>
-              <option value="1.6">1 mile</option>
-              <option value="4.8">3 miles</option>
-              <option value="8.0">5 miles</option>
-              <option value="16.0">10 miles</option>
+              <option value="0.5">0.5 miles</option>
+              <option value="1">1 mile</option>
+              <option value="3">3 miles</option>
+              <option value="5">5 miles</option>
+              <option value="10">10 miles</option>
             </select>
           </div>
         )}

nextjs-app/components/HomeView.tsx

@@ -147,7 +147,7 @@ export function HomeView({ initialSchools, filters, totalSchools }: HomeViewProp
             {searchParams.get('search') && <span className={styles.filterChip}>Search: {searchParams.get('search')}<a href="/" className={styles.chipRemove} onClick={e => { e.preventDefault(); }}>×</a></span>}
             {searchParams.get('local_authority') && <span className={styles.filterChip}>{searchParams.get('local_authority')}</span>}
             {searchParams.get('school_type') && <span className={styles.filterChip}>{searchParams.get('school_type')}</span>}
-            {searchParams.get('postcode') && <span className={styles.filterChip}>Near {searchParams.get('postcode')} ({(parseFloat(searchParams.get('radius') || '1.6') / 1.60934).toFixed(1)} mi)</span>}
+            {searchParams.get('postcode') && <span className={styles.filterChip}>Near {searchParams.get('postcode')} ({parseFloat(searchParams.get('radius') || '1')} mi)</span>}
           </div>
         )}
 
@@ -248,7 +248,7 @@ function CompactSchoolItem({ school, onAddToCompare, isInCompare }: CompactSchoo
           </a>
           {school.distance !== undefined && school.distance !== null && (
             <span className={styles.distanceBadge}>
-              {(school.distance / 1.60934).toFixed(1)} mi
+              {school.distance.toFixed(1)} mi
             </span>
           )}
         </div>

nextjs-app/components/SchoolRow.tsx

@@ -108,7 +108,7 @@ export function SchoolRow({
             )}
           {isLocationSearch && school.distance != null && (
             <span className={styles.distanceBadge}>
-              {(school.distance / 1609.34).toFixed(1)} mi
+              {school.distance.toFixed(1)} mi
             </span>
           )}
         </div>