Refactor ServicesScreen to enhance modal management and localization

- Updated modal state management by introducing separate states for each service modal.
- Changed service titles to localized versions in Turkmen.
- Improved CurrencyConverterModal integration by updating visibility state and placeholder text color for better user experience.

components/CurrencyConverterModal.tsx

@@ -48,6 +48,7 @@ const CurrencyConverterModal: React.FC<CurrencyConverterModalProps> = ({ visible
               style={styles.input}
               keyboardType="numeric"
               placeholder="0.00"
+              placeholderTextColor="#666"
               value={sar}
               onChangeText={handleSarChange}
             />