fix(downloads): restore hardened output scope release gates

Detect stale or foreign files in package-specific extraction directories before starting fresh work while excluding current and atomic ownership markers.

Keep recursive directory inspection confined to the start-conflict boundary and let archive cleanup prune empty package directories directly.

Register German-audio, auto-rename, collection, hybrid, and legacy fixtures through real complete PackageOutputScope records with current method signatures.

Verify plain stops only persist after active work drains, while update-restart parking keeps both its immediate checkpoint and final queued state.

tests/helpers/package-output-scope.ts

@@ -0,0 +1,24 @@
+import path from "node:path";
+import { PackageOutputScope } from "../../src/main/package-output-scope";
+import type { PackageEntry } from "../../src/shared/types";
+
+export function registerPackageCompleteOutputs(pkg: PackageEntry, outputPaths: readonly string[]): PackageOutputScope {
+  const roots = [pkg.outputDir, pkg.extractDir].filter((root): root is string => Boolean(String(root || "").trim()));
+  const scope = new PackageOutputScope(roots);
+  const archivePath = path.resolve(pkg.outputDir || pkg.extractDir, "fixture-source.archive");
+  for (const outputPath of outputPaths) {
+    const relativePath = path.relative(pkg.extractDir, outputPath).replace(/\\/g, "/");
+    scope.add({
+      version: 1,
+      archivePath,
+      entryPath: relativePath && !relativePath.startsWith("../") ? relativePath : path.basename(outputPath),
+      outputPath,
+      state: "complete",
+      disposition: "written"
+    });
+  }
+  pkg.outputProvenanceVersion = 1;
+  pkg.outputRecords = scope.records();
+  pkg.outputCount = scope.records().length;
+  return scope;
+}