feat: Week 1 complete - Linux support + IPC API prep

🎉 Major v2.0 rebuild kickoff - Week 1 accomplished!

## Highlights

### Cross-Platform Support 🌍
- ✅ Linux primary platform (Ubuntu/Debian tested)
- ✅ Windows fully supported
- ✅ macOS experimental support
- ✅ Platform-agnostic path handling (XDG spec)
- ✅ Auto-detection of KiCAD installation

### Infrastructure 🏗️
- ✅ GitHub Actions CI/CD pipeline
- ✅ Pytest framework with 20+ tests
- ✅ Pre-commit hooks (Black, MyPy, ESLint)
- ✅ Automated Linux installation script
- ✅ Enhanced npm scripts

### IPC API Migration Prep 🚀
- ✅ Comprehensive migration plan (30 pages)
- ✅ Backend abstraction layer (800+ lines)
- ✅ Factory pattern with auto-detection
- ✅ SWIG backward compatibility wrapper
- ✅ IPC backend skeleton ready

### Documentation 📚
- ✅ Updated README (Linux installation)
- ✅ CONTRIBUTING.md guide
- ✅ Linux compatibility audit
- ✅ IPC API migration plan
- ✅ Session summaries
- ✅ Platform-specific config templates

## Files Changed

- 27 files created
- ~3,000 lines of code/docs
- 8 comprehensive documentation pages
- 20+ unit tests
- 5 abstraction layer modules

## Next Steps

- Week 2: IPC API migration (project.py → component.py → routing.py)
- Migrate from deprecated SWIG to official IPC API
- JLCPCB/Digikey integration prep

🤖 Generated with Claude Code
https://claude.com/claude-code

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

python/kicad_api/base.py

@@ -0,0 +1,204 @@
+"""
+Abstract base class for KiCAD API backends
+
+Defines the interface that all KiCAD backends must implement.
+"""
+from abc import ABC, abstractmethod
+from pathlib import Path
+from typing import Optional, Dict, Any, List
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+class KiCADBackend(ABC):
+    """Abstract base class for KiCAD API backends"""
+
+    @abstractmethod
+    def connect(self) -> bool:
+        """
+        Connect to KiCAD
+
+        Returns:
+            True if connection successful, False otherwise
+        """
+        pass
+
+    @abstractmethod
+    def disconnect(self) -> None:
+        """Disconnect from KiCAD and clean up resources"""
+        pass
+
+    @abstractmethod
+    def is_connected(self) -> bool:
+        """
+        Check if currently connected to KiCAD
+
+        Returns:
+            True if connected, False otherwise
+        """
+        pass
+
+    @abstractmethod
+    def get_version(self) -> str:
+        """
+        Get KiCAD version
+
+        Returns:
+            Version string (e.g., "9.0.0")
+        """
+        pass
+
+    # Project Operations
+    @abstractmethod
+    def create_project(self, path: Path, name: str) -> Dict[str, Any]:
+        """
+        Create a new KiCAD project
+
+        Args:
+            path: Directory path for the project
+            name: Project name
+
+        Returns:
+            Dictionary with project info
+        """
+        pass
+
+    @abstractmethod
+    def open_project(self, path: Path) -> Dict[str, Any]:
+        """
+        Open an existing KiCAD project
+
+        Args:
+            path: Path to .kicad_pro file
+
+        Returns:
+            Dictionary with project info
+        """
+        pass
+
+    @abstractmethod
+    def save_project(self, path: Optional[Path] = None) -> Dict[str, Any]:
+        """
+        Save the current project
+
+        Args:
+            path: Optional new path to save to
+
+        Returns:
+            Dictionary with save status
+        """
+        pass
+
+    @abstractmethod
+    def close_project(self) -> None:
+        """Close the current project"""
+        pass
+
+    # Board Operations
+    @abstractmethod
+    def get_board(self) -> 'BoardAPI':
+        """
+        Get board API for current project
+
+        Returns:
+            BoardAPI instance
+        """
+        pass
+
+
+class BoardAPI(ABC):
+    """Abstract interface for board operations"""
+
+    @abstractmethod
+    def set_size(self, width: float, height: float, unit: str = "mm") -> bool:
+        """
+        Set board size
+
+        Args:
+            width: Board width
+            height: Board height
+            unit: Unit of measurement ("mm" or "in")
+
+        Returns:
+            True if successful
+        """
+        pass
+
+    @abstractmethod
+    def get_size(self) -> Dict[str, float]:
+        """
+        Get current board size
+
+        Returns:
+            Dictionary with width, height, unit
+        """
+        pass
+
+    @abstractmethod
+    def add_layer(self, layer_name: str, layer_type: str) -> bool:
+        """
+        Add a layer to the board
+
+        Args:
+            layer_name: Name of the layer
+            layer_type: Type ("copper", "technical", "user")
+
+        Returns:
+            True if successful
+        """
+        pass
+
+    @abstractmethod
+    def list_components(self) -> List[Dict[str, Any]]:
+        """
+        List all components on the board
+
+        Returns:
+            List of component dictionaries
+        """
+        pass
+
+    @abstractmethod
+    def place_component(
+        self,
+        reference: str,
+        footprint: str,
+        x: float,
+        y: float,
+        rotation: float = 0,
+        layer: str = "F.Cu"
+    ) -> bool:
+        """
+        Place a component on the board
+
+        Args:
+            reference: Component reference (e.g., "R1")
+            footprint: Footprint library path
+            x: X position (mm)
+            y: Y position (mm)
+            rotation: Rotation angle (degrees)
+            layer: Layer name
+
+        Returns:
+            True if successful
+        """
+        pass
+
+    # Add more abstract methods for routing, DRC, export, etc.
+    # These will be filled in during migration
+
+
+class BackendError(Exception):
+    """Base exception for backend errors"""
+    pass
+
+
+class ConnectionError(BackendError):
+    """Raised when connection to KiCAD fails"""
+    pass
+
+
+class APINotAvailableError(BackendError):
+    """Raised when required API is not available"""
+    pass