Fix JVM extractor: asarUnpack for class/jar files, add unpacked path candidate, default to jvm mode

The JVM sidecar class files were packed inside app.asar where Java
cannot access them. asarUnpack extracts them to app.asar.unpacked/.
Default backend changed from auto to jvm (no legacy fallback).

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "real-debrid-downloader",
-  "version": "1.5.44",
+  "version": "1.5.45",
   "description": "Real-Debrid Downloader Desktop (Electron + React + TypeScript)",
   "main": "build/main/main/main.js",
   "author": "Sucukdeluxe",
@@ -56,6 +56,9 @@
       "resources/extractor-jvm/**/*",
       "package.json"
     ],
+    "asarUnpack": [
+      "resources/extractor-jvm/**/*"
+    ],
     "win": {
       "target": [
         "nsis",