Replace extraction backend with SevenZipJBinding + Zip4j JVM sidecar

- New JVM sidecar (resources/extractor-jvm/) using SevenZipJBinding for
  RAR/7z/TAR and Zip4j for ZIP multipart, matching JDownloader 2 stack
- Auto/JVM/Legacy backend modes via RD_EXTRACT_BACKEND env variable
- Fallback to legacy UnRAR/7z when JVM runtime unavailable
- Fix isJvmRuntimeMissingError false positives on valid extraction errors
- Cache JVM layout resolution to avoid repeated filesystem checks
- Route nested ZIP extraction through JVM backend consistently

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/extractor-jvm.test.ts

@@ -0,0 +1,107 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+import { spawnSync } from "node:child_process";
+import AdmZip from "adm-zip";
+import { afterEach, describe, expect, it } from "vitest";
+import { extractPackageArchives } from "../src/main/extractor";
+
+const tempDirs: string[] = [];
+const originalBackend = process.env.RD_EXTRACT_BACKEND;
+
+function hasJavaRuntime(): boolean {
+  const result = spawnSync("java", ["-version"], { stdio: "ignore" });
+  return result.status === 0;
+}
+
+function hasJvmExtractorRuntime(): boolean {
+  const root = path.join(process.cwd(), "resources", "extractor-jvm");
+  const classesMain = path.join(root, "classes", "com", "sucukdeluxe", "extractor", "JBindExtractorMain.class");
+  const requiredLibs = [
+    path.join(root, "lib", "sevenzipjbinding.jar"),
+    path.join(root, "lib", "sevenzipjbinding-all-platforms.jar"),
+    path.join(root, "lib", "zip4j.jar")
+  ];
+  return fs.existsSync(classesMain) && requiredLibs.every((libPath) => fs.existsSync(libPath));
+}
+
+afterEach(() => {
+  for (const dir of tempDirs.splice(0)) {
+    fs.rmSync(dir, { recursive: true, force: true });
+  }
+  if (originalBackend === undefined) {
+    delete process.env.RD_EXTRACT_BACKEND;
+  } else {
+    process.env.RD_EXTRACT_BACKEND = originalBackend;
+  }
+});
+
+describe("extractor jvm backend", () => {
+  it("extracts zip archives through SevenZipJBinding backend", async () => {
+    if (!hasJavaRuntime() || !hasJvmExtractorRuntime()) {
+      return;
+    }
+
+    process.env.RD_EXTRACT_BACKEND = "jvm";
+
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), "rd-jvm-extract-"));
+    tempDirs.push(root);
+    const packageDir = path.join(root, "pkg");
+    const targetDir = path.join(root, "out");
+    fs.mkdirSync(packageDir, { recursive: true });
+
+    const zipPath = path.join(packageDir, "release.zip");
+    const zip = new AdmZip();
+    zip.addFile("episode.txt", Buffer.from("ok"));
+    zip.writeZip(zipPath);
+
+    const result = await extractPackageArchives({
+      packageDir,
+      targetDir,
+      cleanupMode: "none",
+      conflictMode: "overwrite",
+      removeLinks: false,
+      removeSamples: false
+    });
+
+    expect(result.extracted).toBe(1);
+    expect(result.failed).toBe(0);
+    expect(fs.existsSync(path.join(targetDir, "episode.txt"))).toBe(true);
+  });
+
+  it("respects ask/skip conflict mode in jvm backend", async () => {
+    if (!hasJavaRuntime() || !hasJvmExtractorRuntime()) {
+      return;
+    }
+
+    process.env.RD_EXTRACT_BACKEND = "jvm";
+
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), "rd-jvm-extract-"));
+    tempDirs.push(root);
+    const packageDir = path.join(root, "pkg");
+    const targetDir = path.join(root, "out");
+    fs.mkdirSync(packageDir, { recursive: true });
+    fs.mkdirSync(targetDir, { recursive: true });
+
+    const zipPath = path.join(packageDir, "conflict.zip");
+    const zip = new AdmZip();
+    zip.addFile("same.txt", Buffer.from("new"));
+    zip.writeZip(zipPath);
+
+    const existingPath = path.join(targetDir, "same.txt");
+    fs.writeFileSync(existingPath, "old", "utf8");
+
+    const result = await extractPackageArchives({
+      packageDir,
+      targetDir,
+      cleanupMode: "none",
+      conflictMode: "ask",
+      removeLinks: false,
+      removeSamples: false
+    });
+
+    expect(result.extracted).toBe(1);
+    expect(result.failed).toBe(0);
+    expect(fs.readFileSync(existingPath, "utf8")).toBe("old");
+  });
+});

tests/extractor.test.ts

@@ -2,15 +2,25 @@ import fs from "node:fs";
 import os from "node:os";
 import path from "node:path";
 import AdmZip from "adm-zip";
-import { afterEach, describe, expect, it } from "vitest";
+import { afterEach, beforeEach, describe, expect, it } from "vitest";
 import { buildExternalExtractArgs, collectArchiveCleanupTargets, extractPackageArchives } from "../src/main/extractor";
 
 const tempDirs: string[] = [];
+const originalExtractBackend = process.env.RD_EXTRACT_BACKEND;
+
+beforeEach(() => {
+  process.env.RD_EXTRACT_BACKEND = "legacy";
+});
 
 afterEach(() => {
   for (const dir of tempDirs.splice(0)) {
     fs.rmSync(dir, { recursive: true, force: true });
   }
+  if (originalExtractBackend === undefined) {
+    delete process.env.RD_EXTRACT_BACKEND;
+  } else {
+    process.env.RD_EXTRACT_BACKEND = originalExtractBackend;
+  }
 });
 
 describe("extractor", () => {