feat(upload): enhance upload functionality with chunk management and cancellation support

- Updated Upload.vue to include cancelItem functionality in the upload queue.
- Modified UploadQueue.vue to emit cancel events for individual items.
- Enhanced UploadQueueItem.vue to display cancel button for ongoing uploads.
- Added merge.ts for handling manifest creation and S3 operations for chunk uploads.
- Introduced temp.html for testing multi-threaded chunk uploads with progress tracking.
- Created AGENTS.md for comprehensive project documentation and guidelines.

src/routes/upload/components/UploadQueue.vue

@@ -11,9 +11,10 @@ defineProps<{
 
 const emit = defineEmits<{
     removeItem: [id: string];
+    cancelItem: [id: string];
     publish: [];
     startQueue: [];
-}>();
+}>()
 </script>
 
 <template>
@@ -53,7 +54,7 @@ const emit = defineEmits<{
                 </div>
 
                 <UploadQueueItem v-for="item in items" :key="item.id" :item="item"
-                    @remove="emit('removeItem', $event)" />
+                    @remove="emit('removeItem', $event)" @cancel="emit('cancelItem', $event)" />
             </div>
 
             <div class="p-6 border-t border-border shrink-0">