fix: onboarding button disabled state; feat: update GPS from client profile

app/(app)/clients/[id].tsx

@@ -1,5 +1,6 @@
 import { useState } from 'react';
 import { View, Text, ScrollView, TouchableOpacity, ActivityIndicator, Linking, Alert, TextInput, Modal, KeyboardAvoidingView, Platform } from 'react-native';
+import * as Location from 'expo-location';
 import { SlideToConfirm } from '../../../components/SlideToConfirm';
 import { SafeAreaView } from 'react-native-safe-area-context';
 import { useLocalSearchParams, router } from 'expo-router';
@@ -130,6 +131,7 @@ export default function ClientDetailScreen() {
   const initialTab = (params.tab === 'invoices' ? 'Invoices' : 'Profile') as Tab;
   const [activeTab, setActiveTab] = useState<Tab>(initialTab);
   const [payingInvoice, setPayingInvoice] = useState<any>(null);
+  const [locationLoading, setLocationLoading] = useState(false);
 
   const { data: client, isLoading } = useQuery({
     queryKey: ['client', id],
@@ -172,6 +174,26 @@ export default function ClientDetailScreen() {
     ]);
   };
 
+  const updateLocation = async () => {
+    setLocationLoading(true);
+    try {
+      const { status } = await Location.requestForegroundPermissionsAsync();
+      if (status !== 'granted') {
+        Alert.alert('Permission denied', 'Location permission is required to update coordinates.');
+        return;
+      }
+      const loc = await Location.getCurrentPositionAsync({ accuracy: Location.Accuracy.High });
+      const { latitude: lat, longitude: lng } = loc.coords;
+      await api.patch(`/api/v1/clients/${id}`, { lat, lng });
+      qc.setQueryData(['client', id], (old: any) => ({ ...old, lat, lng }));
+      Alert.alert('Location updated', '📍 GPS coordinates saved successfully.');
+    } catch (e: any) {
+      Alert.alert('Error', 'Could not get location. Make sure GPS is enabled.');
+    } finally {
+      setLocationLoading(false);
+    }
+  };
+
   if (isLoading) {
     return (
       <SafeAreaView style={{ flex: 1, backgroundColor: '#0891B2' }} edges={['top']}>
@@ -256,6 +278,28 @@ export default function ClientDetailScreen() {
                   <Text style={{ fontSize: 13, color: '#CBD5E1', textAlign: 'center' }}>Location is recorded when a technician confirms an installation</Text>
                 </View>
               )}
+
+              {/* Update Location */}
+              <TouchableOpacity
+                onPress={updateLocation}
+                activeOpacity={0.8}
+                style={{
+                  borderWidth: 1.5, borderColor: '#0891B2', borderRadius: 14,
+                  paddingVertical: 14, alignItems: 'center', marginTop: 10,
+                  backgroundColor: '#fff',
+                }}
+              >
+                {locationLoading
+                  ? <ActivityIndicator color="#0891B2" />
+                  : <Text style={{ color: '#0891B2', fontSize: 16, fontWeight: '700' }}>📍 Update Location</Text>
+                }
+              </TouchableOpacity>
+              {client?.lat && client?.lng
+                ? <Text style={{ fontSize: 13, color: '#94A3B8', marginTop: 6, textAlign: 'center' }}>
+                    📍 {Number(client.lat).toFixed(5)}, {Number(client.lng).toFixed(5)}
+                  </Text>
+                : <Text style={{ fontSize: 13, color: '#CBD5E1', marginTop: 6, textAlign: 'center' }}>No location set</Text>
+              }
             </View>
           </ScrollView>
         )}