feat: CodePilot - desktop GUI for Claude Code

Full-featured desktop application built with Next.js + Electron:
- Streaming chat with Claude Code via Agent SDK
- Session management with SQLite persistence
- Project file tree and file preview
- MCP server and custom skills management
- Permission controls with Code/Plan/Ask modes
- Dark/light theme, token tracking
- macOS DMG packaging with electron-builder

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/hooks/usePanel.ts

@@ -0,0 +1,32 @@
+"use client";
+
+import { createContext, useContext } from "react";
+
+export type PanelContent = "files" | "tasks";
+
+export interface PanelContextValue {
+  panelOpen: boolean;
+  setPanelOpen: (open: boolean) => void;
+  panelContent: PanelContent;
+  setPanelContent: (content: PanelContent) => void;
+  workingDirectory: string;
+  setWorkingDirectory: (dir: string) => void;
+  sessionId: string;
+  setSessionId: (id: string) => void;
+  sessionTitle: string;
+  setSessionTitle: (title: string) => void;
+  streamingSessionId: string;
+  setStreamingSessionId: (id: string) => void;
+  pendingApprovalSessionId: string;
+  setPendingApprovalSessionId: (id: string) => void;
+}
+
+export const PanelContext = createContext<PanelContextValue | null>(null);
+
+export function usePanel(): PanelContextValue {
+  const ctx = useContext(PanelContext);
+  if (!ctx) {
+    throw new Error("usePanel must be used within a PanelProvider");
+  }
+  return ctx;
+}