FlightsMapFilter: reset toggles when departure cleared; add disabled-title hint

Angular's FlightsMapFiltersStateService.setDeparture(undefined) also
resets domestic/international/connections to false — none of them make
sense without a departure anchor. React now mirrors that reset on clear
so a re-opened filter doesn't show phantom 'on' toggles.

Also added a `title` attribute on each disabled toggle that points
users to the missing city input. The toggles are still disabled (per
Angular behavior) but the hint explains *why* they can't be toggled,
which was the source of confusion in the 'feature not fully
implemented' report.

src/features/flights-map/components/FlightsMapFilter.tsx

@@ -152,11 +152,23 @@ export const FlightsMapFilter: FC<FlightsMapFilterProps> = ({
         placeholder={t("FLIGHTS-MAP.FILTER_DEPARTURE_PLACEHOLDER")}
         value={value.departure ?? ""}
         onChange={(code) => {
-          onChange({
-            ...value,
-            departure: code || undefined,
-            arrival: undefined,
-          });
+          // Mirrors Angular FlightsMapFiltersStateService.setDeparture:
+          // clearing departure also resets the three toggles (domestic,
+          // international, connections) back to false since none of them
+          // apply without a departure anchor. Keeping them on would leave
+          // the disabled chip in an "on" visual state after re-opening.
+          if (!code) {
+            onChange({
+              ...value,
+              departure: undefined,
+              arrival: undefined,
+              domestic: false,
+              international: false,
+              connections: false,
+            });
+            return;
+          }
+          onChange({ ...value, departure: code, arrival: undefined });
         }}
         dictionaries={dictionaries}
         onLocate={handleLocate}
@@ -207,8 +219,15 @@ export const FlightsMapFilter: FC<FlightsMapFilterProps> = ({
       </div>
 
       <div className="flights-map-filter__toggles">
+        {/* Mirrors Angular: domestic/international toggles require a
+            departure city; the connections toggle also requires an
+            arrival city (you can only route-search with both cities).
+            We add `title` hints so disabled toggles explain why they
+            can't be toggled — Angular's toggle-switch doesn't surface
+            this, but the hint is a pure UX win at no parity cost. */}
         <label
           className={`flights-map-filter__toggle${!value.departure ? " flights-map-filter__toggle--disabled" : ""}`}
+          title={!value.departure ? t("FLIGHTS-MAP.FILTER_DEPARTURE_PLACEHOLDER") : undefined}
         >
           <input
             type="checkbox"
@@ -223,6 +242,7 @@ export const FlightsMapFilter: FC<FlightsMapFilterProps> = ({
 
         <label
           className={`flights-map-filter__toggle${!value.departure ? " flights-map-filter__toggle--disabled" : ""}`}
+          title={!value.departure ? t("FLIGHTS-MAP.FILTER_DEPARTURE_PLACEHOLDER") : undefined}
         >
           <input
             type="checkbox"
@@ -237,6 +257,13 @@ export const FlightsMapFilter: FC<FlightsMapFilterProps> = ({
 
         <label
           className={`flights-map-filter__toggle${!(value.departure && value.arrival) ? " flights-map-filter__toggle--disabled" : ""}`}
+          title={
+            !value.departure
+              ? t("FLIGHTS-MAP.FILTER_DEPARTURE_PLACEHOLDER")
+              : !value.arrival
+                ? t("FLIGHTS-MAP.FILTER_ARRIVAL_PLACEHOLDER")
+                : undefined
+          }
         >
           <input
             type="checkbox"