Add Clide project structure and initial implementation

Set up the TUI IDE wrapper for Claude Code CLI with:
- Core app structure using Textual framework
- Panel architecture (sidebar, workspace, claude, context)
- Theme system with 22 built-in themes (Summer Night default)
- Pydantic models for configuration and data
- Makefile for development commands
- Project documentation and specs

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

tests/harnesses/controller_harness.py

@@ -0,0 +1,97 @@
+"""Controller isolation test harness for Clide."""
+
+from typing import TYPE_CHECKING, Any, Optional
+from unittest.mock import AsyncMock, MagicMock
+
+from textual.message import Message
+
+if TYPE_CHECKING:
+    from clide.controllers.base import BaseController
+
+
+class MockApp:
+    """Minimal mock of a Textual App for controller testing."""
+
+    def __init__(self) -> None:
+        self.messages: list[Message] = []
+        self.post_message = MagicMock(side_effect=self._capture_message)
+
+    def _capture_message(self, message: Message) -> None:
+        self.messages.append(message)
+
+    def get_messages(self, message_type: Optional[type] = None) -> list[Message]:
+        """Get captured messages, optionally filtered by type."""
+        if message_type is None:
+            return self.messages.copy()
+        return [m for m in self.messages if isinstance(m, message_type)]
+
+    def clear_messages(self) -> None:
+        """Clear captured messages."""
+        self.messages.clear()
+
+
+class ControllerHarness:
+    """Test harness for isolated controller testing.
+
+    Provides a mock app environment for testing controllers without
+    the full Textual application overhead.
+
+    Usage:
+        harness = ControllerHarness()
+        controller = GitController(harness.mock_app)
+        await controller.initialize()
+        await controller.refresh_status()
+        messages = harness.get_messages()
+    """
+
+    def __init__(self) -> None:
+        self._mock_app = MockApp()
+        self._controllers: list["BaseController"] = []
+        self._mocks: dict[str, Any] = {}
+
+    @property
+    def mock_app(self) -> MockApp:
+        """Get the mock app for controller injection."""
+        return self._mock_app
+
+    def register_controller(self, controller: "BaseController") -> None:
+        """Register a controller for lifecycle management."""
+        self._controllers.append(controller)
+
+    async def initialize_all(self) -> None:
+        """Initialize all registered controllers."""
+        for controller in self._controllers:
+            await controller.initialize()
+
+    async def shutdown_all(self) -> None:
+        """Shutdown all registered controllers."""
+        for controller in self._controllers:
+            await controller.shutdown()
+
+    def get_messages(self, message_type: Optional[type] = None) -> list[Message]:
+        """Get messages posted to the mock app."""
+        return self._mock_app.get_messages(message_type)
+
+    def clear_messages(self) -> None:
+        """Clear all captured messages."""
+        self._mock_app.clear_messages()
+
+    def add_mock(self, name: str, mock: Any) -> None:
+        """Add a named mock for dependency injection.
+
+        Args:
+            name: Identifier for the mock
+            mock: Mock object or AsyncMock
+        """
+        self._mocks[name] = mock
+
+    def get_mock(self, name: str) -> Any:
+        """Retrieve a named mock."""
+        return self._mocks.get(name)
+
+    def create_async_mock(self, return_value: Any = None) -> AsyncMock:
+        """Create an AsyncMock with optional return value."""
+        mock = AsyncMock()
+        if return_value is not None:
+            mock.return_value = return_value
+        return mock