Lots of improvements

frontend/src/hooks/useTravelTime.ts

@@ -16,6 +16,8 @@ export interface TravelTimeEntry {
   slug: string;
   label: string;
   timeRange: [number, number] | null;
+  /** Use best-case (5th percentile) travel time instead of median. Transit only. */
+  useBest: boolean;
 }
 
 /** Field key matching the backend response: tt_{mode}_{slug} */
@@ -33,7 +35,7 @@ export function useTravelTime(initial?: TravelTimeInitial) {
   const handleAddEntry = useCallback((mode: TransportMode) => {
     setEntries((prev) => [
       ...prev,
-      { mode, slug: '', label: '', timeRange: null },
+      { mode, slug: '', label: '', timeRange: null, useBest: false },
     ]);
   }, []);
 
@@ -63,6 +65,17 @@ export function useTravelTime(initial?: TravelTimeInitial) {
     []
   );
 
+  const handleToggleBest = useCallback(
+    (index: number) => {
+      setEntries((prev) =>
+        prev.map((entry, i) =>
+          i === index ? { ...entry, useBest: !entry.useBest, timeRange: null } : entry
+        )
+      );
+    },
+    []
+  );
+
   /** Entries that have a destination selected (slug is set) */
   const activeEntries = useMemo(
     () => entries.filter((e) => e.slug !== ''),
@@ -76,5 +89,6 @@ export function useTravelTime(initial?: TravelTimeInitial) {
     handleRemoveEntry,
     handleSetDestination,
     handleTimeRangeChange,
+    handleToggleBest,
   };
 }