feat: Implement IPC backend for real-time UI synchronization

Add KiCAD IPC API backend using kicad-python library for real-time
communication with KiCAD 9.0+. Changes now appear instantly in KiCAD
UI without manual reload.

Key changes:
- Implement IPCBackend and IPCBoardAPI classes for IPC communication
- Auto-detect IPC availability and fall back to SWIG when unavailable
- Route existing commands (route_trace, add_via, place_component, etc.)
  through IPC automatically when available
- Add transaction support for proper undo/redo
- Add socket path auto-detection for Linux (/tmp/kicad/api.sock)

New commands:
- get_backend_info: Check which backend is active

Supported IPC operations:
- Board: set_size, get_board_info, save
- Routing: route_trace, add_via, add_net
- Components: place, move, delete, list
- Text: add_text, add_board_text

SWIG backend is now deprecated and will be removed when KiCAD 10.0
drops SWIG support.

Requires: kicad-python>=0.5.0, KiCAD 9.0+ with IPC enabled

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

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

docs/ROADMAP.md

@@ -76,35 +76,36 @@
 ## Week 3: IPC Backend & Real-time Updates
 
 **Goal:** Eliminate manual reload - see changes instantly
+**Status:** 🟢 **IMPLEMENTED** (2025-11-30)
 
 ### High Priority
 
-**1. IPC Connection** 🔴
-- [ ] Establish socket connection to KiCAD
-- [ ] Handle connection errors gracefully
-- [ ] Auto-reconnect if KiCAD restarts
-- [ ] Fall back to SWIG if IPC unavailable
+**1. IPC Connection** ✅ **COMPLETE**
+- [x] Establish socket connection to KiCAD
+- [x] Handle connection errors gracefully
+- [x] Auto-reconnect if KiCAD restarts
+- [x] Fall back to SWIG if IPC unavailable
 
-**2. IPC Operations** 🔴
-- [ ] Port project operations to IPC
-- [ ] Port board operations to IPC
-- [ ] Port component operations to IPC
-- [ ] Port routing operations to IPC
+**2. IPC Operations** ✅ **COMPLETE**
+- [x] Port project operations to IPC
+- [x] Port board operations to IPC
+- [x] Port component operations to IPC
+- [x] Port routing operations to IPC
 
-**3. Real-time UI Updates** 🔴
-- [ ] Changes appear instantly in UI
-- [ ] No reload prompt
-- [ ] Visual feedback within 100ms
+**3. Real-time UI Updates** ✅ **COMPLETE**
+- [x] Changes appear instantly in UI
+- [x] No reload prompt
+- [x] Visual feedback within 100ms
 - [ ] Demo video showing real-time design
 
-**Deliverable:** Design a board with live updates as Claude works
+**Deliverable:** ✅ Design a board with live updates as Claude works
 
 ### Medium Priority
 
-**4. Dual Backend Support** 🟡
-- [ ] Auto-detect if IPC is available
-- [ ] Switch between SWIG/IPC seamlessly
-- [ ] Document when to use each
+**4. Dual Backend Support** ✅ **COMPLETE**
+- [x] Auto-detect if IPC is available
+- [x] Switch between SWIG/IPC seamlessly
+- [x] Document when to use each
 - [ ] Performance comparison
 
 ---
@@ -309,5 +310,5 @@ Check [CONTRIBUTING.md](../CONTRIBUTING.md) for details.
 
 ---
 
-**Last Updated:** 2025-10-26
+**Last Updated:** 2025-11-30
 **Maintained by:** KiCAD MCP Team