Drop MOW fallback on flights-map, match Angular's geo-only seed

Angular's FlightsMapFilterComponent only sets departure when
UserLocationService.location emits an actual position — there's no
fallback to Moscow. Removing the React fallback aligns the empty
initial state (no splines drawn before user input).

src/features/flights-map/hooks/useGeolocationDefault.test.tsx

@@ -126,20 +126,23 @@ describe("useGeolocationDefault", () => {
     expect(lastState.departure).toBeUndefined();
   });
 
-  it("falls back to MOW when geolocation permission is denied", () => {
+  it("leaves departure empty when geolocation permission is denied", () => {
     installGeolocation(errorMock());
     renderHook(() =>
       useGeolocationDefault(dictionaries, lastState, setFilterState),
     );
-    expect(lastState.departure).toBe("MOW");
+    // Angular's FlightsMapFilterComponent only seeds departure when
+    // UserLocationService.location emits — there's no fallback when
+    // the user denies geo access.
+    expect(lastState.departure).toBeUndefined();
   });
 
-  it("falls back to MOW when navigator.geolocation is missing", () => {
+  it("leaves departure empty when navigator.geolocation is missing", () => {
     installGeolocation(undefined);
     renderHook(() =>
       useGeolocationDefault(dictionaries, lastState, setFilterState),
     );
-    expect(lastState.departure).toBe("MOW");
+    expect(lastState.departure).toBeUndefined();
   });
 
   it("does nothing when dictionaries is null at callback time", () => {

src/features/flights-map/hooks/useGeolocationDefault.ts

@@ -2,7 +2,9 @@
  * Sets the flights-map filter's departure to the nearest city based on
  * browser geolocation, if the user has not already typed a departure or
  * arrival. Fires once per mount. Silent on permission denial or missing
- * geolocation API. Matches Angular `UserLocationService` + `DictionariesService.locate`.
+ * geolocation API. Matches Angular `FlightsMapFilterComponent.ngOnInit`
+ * which only seeds departure when `UserLocationService.location` emits
+ * — i.e. on actual geo permission, with no MOW fallback.
  */
 
 import { useEffect, useRef } from "react";
@@ -20,7 +22,6 @@ export function useGeolocationDefault(
   ) => void,
 ): void {
   const appliedRef = useRef(false);
-  const fallbackAppliedRef = useRef(false);
   const dictRef = useRef(dictionaries);
   dictRef.current = dictionaries;
   const filterRef = useRef(filterState);
@@ -28,26 +29,6 @@ export function useGeolocationDefault(
   const setFilterRef = useRef(setFilterState);
   setFilterRef.current = setFilterState;
 
-  // MOW fallback seed: fires as soon as dictionaries load so the
-  // orange Moscow marker shows even without geo permission. Runs at
-  // most once. Geo response below may overwrite with a closer city.
-  useEffect(() => {
-    if (fallbackAppliedRef.current) return;
-    if (!dictionaries) return;
-    if (filterRef.current.departure || filterRef.current.arrival) {
-      fallbackAppliedRef.current = true;
-      return;
-    }
-    const moscow = dictionaries.cityByCode.get("MOW");
-    if (!moscow) return;
-    fallbackAppliedRef.current = true;
-    setFilterRef.current((prev) =>
-      prev.departure || prev.arrival
-        ? prev
-        : { ...prev, departure: "MOW" },
-    );
-  }, [dictionaries]);
-
   useEffect(() => {
     if (appliedRef.current) return;
     if (typeof navigator === "undefined" || !navigator.geolocation) {
@@ -62,10 +43,6 @@ export function useGeolocationDefault(
         const d = dictRef.current;
         const f = filterRef.current;
         if (!d) return;
-        // Don't override anything that's already in state — neither
-        // the MOW fallback above nor an explicit user choice. Matches
-        // Angular which keeps the orange marker on Moscow once the
-        // initial render has placed it.
         if (f.departure || f.arrival) return;
 
         const city = findCityByCoord(
@@ -82,8 +59,9 @@ export function useGeolocationDefault(
         );
       },
       () => {
-        // Silent: permission denied / timeout / unavailable. The MOW
-        // fallback above already seeded the marker.
+        // Silent: permission denied / timeout / unavailable. Matches
+        // Angular which leaves the filter empty when no location is
+        // available.
       },
       { enableHighAccuracy: false, timeout: 5000 },
     );