feat(hunt): track walking distance via GPS, show live locations on map

Add foreground-only GPS distance tracking for hunts

app/pages/hunt/[huntSlug]/[questSlug]/index.vue

@@ -74,6 +74,14 @@ const answer = ref(data.value?.answer?.text);
 const final = ref(data.value?.answer?.final || false);
 const privateImage = ref(data.value?.answer?.picture?.private ?? false);
 
+const trackableHunt = data.value?.hunt ?? null;
+const geo = trackableHunt ? useGeoTracking(trackableHunt) : null;
+
+// Submit-location slice: independent of the tracking watch loop. The checkbox
+// is offered only when the user consented and the hunt is tracking-eligible.
+const sendLocation = ref(unref(geo?.consented?.value ?? false));
+const locationNotice = ref('');
+
 const privateChanged = computed(
   () => (data.value?.answer?.picture?.private ?? false) !== privateImage.value
 );
@@ -105,6 +113,7 @@ useEventListener(window, 'beforeunload', (ev) => {
 async function submit() {
   uploading.value = true;
   submitError.value = '';
+  locationNotice.value = '';
   uploadProgress.value = 0;
 
   const body = new FormData();
@@ -127,6 +136,16 @@ async function submit() {
     compressing.value = false;
     body.set('image', compressedImage);
   }
+  if (sendLocation.value && geo) {
+    try {
+      const pos = await geo.getPosition();
+      body.set('lat', String(pos.lat));
+      body.set('lon', String(pos.lon));
+    } catch {
+      // Non-blocking: submit without the location and tell the user.
+      locationNotice.value = t('page.quest.location_unavailable');
+    }
+  }
   const xhr = new XMLHttpRequest();
 
   try {
@@ -149,6 +168,7 @@ async function submit() {
     answer.value = data.value?.answer?.text;
     privateImage.value = data.value?.answer?.picture?.private ?? false;
     newImage.value = undefined;
+    sendLocation.value = false;
   } catch (e) {
     if (xhr.status === 418) {
       submitError.value = t('page.quest.already_finalized');
@@ -353,7 +373,20 @@ async function submit() {
                 :label="t('page.quest.finalize')"
                 :messages="t('page.quest.finalize_explain')"
               />
+              <VaCheckbox
+                v-if="geo?.gate"
+                v-model="sendLocation"
+                :disabled="uploading || data.answer?.final"
+                :label="t('page.quest.send_location')"
+                :messages="t('page.quest.send_location_explain')"
+              />
 
+              <VaAlert
+                v-if="locationNotice.length > 0"
+                color="warning"
+                class="w-full text-center"
+                >{{ locationNotice }}</VaAlert
+              >
               <VaAlert
                 v-if="submitError.length > 0"
                 color="danger"
@@ -367,7 +400,8 @@ async function submit() {
                     newImage ||
                     data.answer?.text !== answer ||
                     data.answer?.final !== final ||
-                    privateChanged
+                    privateChanged ||
+                    sendLocation
                   ) || uploading
                 "
                 :loading="uploading"