Fix infinite spawn loop on Windows PyInstaller builds

CRITICAL FIX: Added multiprocessing.freeze_support() to prevent the
frozen executable from spawning infinite copies of itself on Windows.

The issue:
When PyInstaller bundles Python apps that use multiprocessing (which
PyTorch, faster-whisper, and RealtimeSTT all use), Windows treats each
spawn as a new process that re-executes the script. Without freeze_support(),
this creates an infinite loop of processes spawning until the system crashes.

The fix:
- Added multiprocessing.freeze_support() at the very top of main.py
- Called before any imports that might use multiprocessing
- Windows-only (wrapped in sys.platform check)
- Must be before QApplication or any Qt imports

This is a standard requirement for all PyInstaller apps that use
multiprocessing on Windows.

Resolves: App spawns infinite copies when running from PyInstaller build

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

main.py

@@ -8,8 +8,14 @@ optional multi-user server synchronization.
 """
 
 import sys
+import multiprocessing
 from pathlib import Path
 
+# CRITICAL: Must be called before anything else on Windows with PyInstaller
+# This prevents the infinite spawning loop when the frozen executable runs
+if sys.platform == 'win32':
+    multiprocessing.freeze_support()
+
 # Add project root to Python path
 project_root = Path(__file__).parent
 sys.path.insert(0, str(project_root))