fix: address code review findings

internal/cache/preferences.go

@@ -107,15 +107,6 @@ func (p *Preferences) AddSavedCity(ctx context.Context, userID, cityCode, cityNa
 
 // RemoveSavedCity removes a city from the user's saved cities.
 func (p *Preferences) RemoveSavedCity(ctx context.Context, userID, cityCode string) error {
-	key := &CacheKey{
-		Kind:    "prefs:saved_city:" + userID,
-		Code:    userID,
-		From:    "",
-		To:      "",
-		Date:    "",
-		Request: "",
-	}
-
 	// Load existing cities
 	cities, err := p.GetSavedCities(ctx, userID)
 	if err != nil {
@@ -132,6 +123,10 @@ func (p *Preferences) RemoveSavedCity(ctx context.Context, userID, cityCode stri
 
 	if len(result) == 0 {
 		// If no cities left, delete the key
+		key := &CacheKey{
+			Kind: "prefs:saved_city:" + userID,
+			Code: userID,
+		}
 		return p.store.Delete(ctx, key)
 	}
 
@@ -141,6 +136,10 @@ func (p *Preferences) RemoveSavedCity(ctx context.Context, userID, cityCode stri
 		return err
 	}
 
+	key := &CacheKey{
+		Kind: "prefs:saved_city:" + userID,
+		Code: userID,
+	}
 	return p.store.Set(ctx, key, data, PreferenceTTL)
 }