Add rider/driver role selection after sign-up

- users.role column (+ migration in seed script)
- /(api)/user: GET role by clerkId, PATCH to set role
- Role selection screen; drivers get placeholder driver-home
- Root index routes by role; hardened location handling on home

app/(root)/(tabs)/home.tsx

@@ -48,24 +48,37 @@ const Home = () => {
 
   useEffect(() => {
     const requestLocation = async () => {
-      let { status } = await Location.requestForegroundPermissionsAsync();
+      try {
+        let { status } = await Location.requestForegroundPermissionsAsync();
 
-      if (status !== "granted") return setHasPermissions(false);
+        if (status !== "granted") return setHasPermissions(false);
 
-      setHasPermissions(true);
+        setHasPermissions(true);
 
-      let location = await Location.getCurrentPositionAsync();
+        let location = await Location.getCurrentPositionAsync();
 
-      const address = await Location.reverseGeocodeAsync({
-        longitude: location.coords?.longitude,
-        latitude: location.coords?.latitude,
-      });
+        let addressText = "Unknown location";
+        try {
+          const address = await Location.reverseGeocodeAsync({
+            longitude: location.coords?.longitude,
+            latitude: location.coords?.latitude,
+          });
+          if (address[0]) {
+            addressText = `${address[0].name}, ${address[0].region}`;
+          }
+        } catch (geocodeErr) {
+          console.log("[REVERSE_GEOCODE]: ", geocodeErr);
+        }
 
-      setUserLocation({
-        latitude: location.coords.latitude,
-        longitude: location.coords.longitude,
-        address: `${address[0].name}, ${address[0].region}`,
-      });
+        setUserLocation({
+          latitude: location.coords.latitude,
+          longitude: location.coords.longitude,
+          address: addressText,
+        });
+      } catch (err) {
+        console.log("[LOCATION]: ", err);
+        setHasPermissions(false);
+      }
     };
 
     requestLocation();
@@ -143,7 +156,16 @@ const Home = () => {
             </Text>
 
             <View className="flex flex-row items-center bg-transparent h-[300px]">
-              {hasPermissions && <Map />}
+              {hasPermissions ? (
+                <Map />
+              ) : (
+                <View className="flex-1 items-center justify-center bg-white rounded-2xl h-full">
+                  <Text className="text-general-200 text-center font-JakartaMedium px-5">
+                    Location access is off.{"\n"}Enable it in your device
+                    settings to see nearby drivers.
+                  </Text>
+                </View>
+              )}
             </View>
 
             <Text className="text-xl font-JakartaBold mt-5 mb-3">