Add persistent JVM daemon for extraction, fix caching with Set+Array

- JVM extractor now supports --daemon mode: starts once, processes
  multiple archives via stdin JSON protocol, eliminating ~5s JVM boot
  per archive
- TypeScript side: daemon manager starts JVM once, sends requests via
  stdin, falls back to spawning new process if daemon is busy
- Fix extraction progress caching: replaced Object.create(null) + in
  operator with Set<string> + linear Array scan — both Map.has() and
  the in operator mysteriously failed to find keys that were just set
- Daemon auto-shutdown on app quit via shutdownDaemon() in before-quit

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

src/main/main.ts

@@ -7,7 +7,7 @@ import { IPC_CHANNELS } from "../shared/ipc";
 import { getLogFilePath, logger } from "./logger";
 import { APP_NAME } from "./constants";
 import { extractHttpLinksFromText } from "./utils";
-import { cleanupStaleSubstDrives } from "./extractor";
+import { cleanupStaleSubstDrives, shutdownDaemon } from "./extractor";
 
 /* ── IPC validation helpers ────────────────────────────────────── */
 function validateString(value: unknown, name: string): string {
@@ -515,6 +515,7 @@ app.on("before-quit", () => {
   if (updateQuitTimer) { clearTimeout(updateQuitTimer); updateQuitTimer = null; }
   stopClipboardWatcher();
   destroyTray();
+  shutdownDaemon();
   try {
     controller.shutdown();
   } catch (error) {