fix : load Gitea URL on modal open instead of onMounted

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/components/task/TaskModal.vue

@@ -326,8 +326,8 @@ watch(() => props.task, (task) => {
     }
 })
 
-onMounted(async () => {
-    if (props.task?.project?.giteaOwner && props.task?.project?.giteaRepo) {
+watch(() => props.modelValue, async (open) => {
+    if (open && props.task?.project?.giteaOwner && props.task?.project?.giteaRepo && !giteaUrl.value) {
         try {
             const settings = await getGiteaSettings()
             giteaUrl.value = settings.url ?? ''