Restore package-based link collector without blocking DLC drops

Reintroduce expandable collector packages, background metadata enrichment, filters, selection, and controlled queue transfer. Keep DLC files dropped outside the collector on the direct addContainers path without settings persistence or metadata waits. Protect collector state with stable URL identities, non-degrading metadata merges, and per-URL generations so stale enrichment responses cannot overwrite newer data or resurrect removed links.

tests/collector-enrichment.test.ts

@@ -0,0 +1,37 @@
+import { describe, expect, it } from "vitest";
+import {
+  beginCollectorEnrichment,
+  filterCurrentCollectorEnrichment
+} from "../src/renderer/collector-enrichment";
+import type { CollectorPackage } from "../src/shared/collector";
+
+function collectorPackage(url: string, status: "ready" | "offline" | "unknown" = "unknown"): CollectorPackage {
+  return {
+    id: `package-${url}`,
+    name: "Paket",
+    nameSource: "inferred",
+    addedAt: 1,
+    links: [{
+      id: `link-${url}`,
+      url,
+      fileName: "download.bin",
+      fileSizeBytes: null,
+      hoster: "example",
+      availability: status === "ready" ? "online" : status,
+      status,
+      addedAt: 1
+    }]
+  };
+}
+
+describe("collector enrichment generations", () => {
+  it("rejects an older response after the same URL starts a newer enrichment", () => {
+    const current = new Map<string, number>();
+    const packages = [collectorPackage("https://example.test/file")];
+    const first = beginCollectorEnrichment(packages, current);
+    const second = beginCollectorEnrichment(packages, current);
+
+    expect(filterCurrentCollectorEnrichment([collectorPackage("https://example.test/file", "offline")], first, current)).toEqual([]);
+    expect(filterCurrentCollectorEnrichment([collectorPackage("https://example.test/file", "ready")], second, current)).toHaveLength(1);
+  });
+});