chore: add drag-and-drop box to Launch page

src/lib/dropZone.svelte.ts

@@ -0,0 +1,52 @@
+import { listen } from "@tauri-apps/api/event";
+import { onDestroy } from "svelte";
+
+type TauriDragDropEvent = {
+  paths: string[];
+  position: { x: number; y: number };
+};
+
+export const useDropZone = ({ onDrop }: { onDrop: (paths: string[]) => void }) => {
+  let element = $state<HTMLDivElement | null>(null);
+  let dragIn = $state(false);
+  let isDraggingOverApp = $state(false);
+
+  const isOver = (x: number, y: number) => {
+    if (!element) return false;
+    const el = document.elementFromPoint(x, y);
+    return element === el || element.contains(el);  // ← fix
+  };
+
+  const dropUnlisten = listen<TauriDragDropEvent>("tauri://drag-drop", (e) => {
+    const { x, y } = e.payload.position;
+    if (isOver(x, y)) {
+      onDrop(e.payload.paths);
+    }
+    dragIn = false;
+    isDraggingOverApp = false;
+  });
+
+  const overUnlisten = listen<TauriDragDropEvent>("tauri://drag-over", (e) => {
+    const { x, y } = e.payload.position;
+    isDraggingOverApp = true;
+    dragIn = isOver(x, y);
+  });
+
+  const leaveUnlisten = listen("tauri://drag-leave", () => {
+    dragIn = false;
+    isDraggingOverApp = false;
+  });
+
+  onDestroy(async () => {
+    (await dropUnlisten)();
+    (await overUnlisten)();
+    (await leaveUnlisten)();
+  });
+
+  return {
+    get ref() { return element; },
+    set ref(el: HTMLDivElement | null) { element = el; },
+    get dragIn() { return dragIn; },
+    get isDraggingOverApp() { return isDraggingOverApp; },
+  };
+};