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/templates/template_with_symbols.kicad_sch

@@ -1,6 +1,6 @@
 (kicad_sch (version 20230121) (generator "KiCAD-MCP-Server")
 
-  (uuid 00000000-0000-0000-0000-000000000000)
+  (uuid a1b2c3d4-e5f6-4a5b-8c9d-0e1f2a3b4c5d)
 
   (paper "A4")