fix: Address critical Windows compatibility and JLCPCB issues (#36, #37, #35)

Phase 1 critical fixes addressing three high-priority issues:

Issue #36 - Windows IPC backend crash (os.getuid not available):
- Add platform detection to skip Unix-specific socket paths on Windows
- Use hasattr check before calling os.getuid()
- Windows now uses auto-detect fallback (named pipes)
- Maintains full Unix socket support on Linux/macOS

Issue #37 - Windows schematic file creation broken:
- Generate unique UUIDs instead of invalid all-zeros UUID
- Add explicit UTF-8 encoding for cross-platform compatibility
- Force Unix line endings (LF) to prevent Windows CRLF issues
- Update template file with valid placeholder UUID
- Fix hardcoded /tmp/ paths in wire_manager.py and pin_locator.py

Issue #35 - JLCPCB download limited to 100 parts:
- Change batch_size from 1000 to 100 to match tscircuit API limit
- Remove premature loop termination when batch < batch_size
- Add documentation explaining API limitation
- Expected result: Full ~2.5M part catalog download (40-60 minutes)

All changes maintain backward compatibility and include detailed comments.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

python/commands/pin_locator.py

@@ -7,6 +7,7 @@ Uses S-expression parsing to extract pin data from symbol definitions.
 
 import logging
 import math
+import tempfile
 from pathlib import Path
 from typing import List, Tuple, Optional, Dict
 import sexpdata
@@ -314,8 +315,8 @@ if __name__ == '__main__':
     print("PIN LOCATOR TEST")
     print("=" * 80)
 
-    # Create test schematic with components
-    test_path = Path('/tmp/test_pin_locator.kicad_sch')
+    # Create test schematic with components (cross-platform temp directory)
+    test_path = Path(tempfile.gettempdir()) / 'test_pin_locator.kicad_sch'
     template_path = Path('/home/chris/MCP/KiCAD-MCP-Server/python/templates/template_with_symbols_expanded.kicad_sch')
 
     shutil.copy(template_path, test_path)