fix(collector): restore direct DLC drag imports

Resolve dropped file paths through Electron webUtils, send dragged DLC containers directly to Downloads, and keep explicit collector imports bounded so metadata enrichment cannot leave the interface permanently busy.

tests/collector-drop.test.ts

@@ -0,0 +1,35 @@
+import { describe, expect, it, vi } from "vitest";
+import { importDroppedDlcFiles, resolveDroppedDlcPaths } from "../src/renderer/collector-drop";
+
+describe("collector DLC drop", () => {
+  it("resolves DLC paths through the preload bridge instead of File.path", () => {
+    const first = { name: "first.dlc" } as File;
+    const ignored = { name: "notes.txt" } as File;
+    const second = { name: "SECOND.DLC" } as File;
+    const getPath = vi.fn((file: File) => file === first ? "C:\\Drops\\first.dlc" : "C:\\Drops\\second.dlc");
+
+    expect(resolveDroppedDlcPaths([first, ignored, second], getPath)).toEqual([
+      "C:\\Drops\\first.dlc",
+      "C:\\Drops\\second.dlc"
+    ]);
+    expect(getPath.mock.calls.map(([file]) => file)).toEqual([first, second]);
+  });
+
+  it("ignores files whose native path cannot be resolved", () => {
+    const file = { name: "broken.dlc" } as File;
+
+    expect(resolveDroppedDlcPaths([file], () => "")).toEqual([]);
+    expect(resolveDroppedDlcPaths([file], () => { throw new Error("unavailable"); })).toEqual([]);
+  });
+
+  it("imports dropped DLC files directly into Downloads without collector analysis", async () => {
+    const file = { name: "package.dlc" } as File;
+    const addContainers = vi.fn(async () => ({ addedPackages: 2, addedLinks: 16 }));
+
+    await expect(importDroppedDlcFiles([file], () => "C:\\Drops\\package.dlc", addContainers)).resolves.toEqual({
+      addedPackages: 2,
+      addedLinks: 16
+    });
+    expect(addContainers).toHaveBeenCalledWith(["C:\\Drops\\package.dlc"]);
+  });
+});