refactor: clean up comments and unused code in various files

src/screens/RegisterScreen.js

@@ -90,7 +90,6 @@ const RegisterScreen = ({ navigation }) => {
             />
           </View>
 
-          {/* Create Account button – blue */}
           <TouchableOpacity
             style={[styles.primaryButton, { backgroundColor: theme.primary, borderColor: theme.border }, loading && styles.buttonDisabled]}
             onPress={handleRegister}
@@ -101,7 +100,6 @@ const RegisterScreen = ({ navigation }) => {
             )}
           </TouchableOpacity>
 
-          {/* Back to Login button – white/outlined */}
           <TouchableOpacity
             style={[styles.secondaryButton, { backgroundColor: theme.background, borderColor: theme.border }]}
             onPress={() => navigation.navigate('Login')}