feat: initial commit - Scrapyd UI web interface

- Next.js 16.0.1 + React 19.2.0 + Tailwind CSS 4.1.16
- Complete Scrapyd API integration (all 12 endpoints)
- Dashboard with real-time job monitoring
- Projects management (upload, list, delete)
- Spiders management with scheduling
- Jobs monitoring with filtering and cancellation
- System status monitoring
- Dark/light theme toggle with next-themes
- Server-side authentication via environment variables
- Docker deployment with multi-stage builds
- GitHub Actions CI/CD workflow

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

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

components/theme-toggle.tsx

@@ -0,0 +1,32 @@
+"use client";
+
+import * as React from "react";
+import { Moon, Sun } from "lucide-react";
+import { useTheme } from "next-themes";
+
+import { Button } from "@/components/ui/button";
+
+export function ThemeToggle() {
+  const { theme, setTheme } = useTheme();
+  const [mounted, setMounted] = React.useState(false);
+
+  React.useEffect(() => {
+    setMounted(true);
+  }, []);
+
+  if (!mounted) {
+    return <Button variant="ghost" size="icon" disabled />;
+  }
+
+  return (
+    <Button
+      variant="ghost"
+      size="icon"
+      onClick={() => setTheme(theme === "light" ? "dark" : "light")}
+    >
+      <Sun className="h-5 w-5 rotate-0 scale-100 transition-all dark:-rotate-90 dark:scale-0" />
+      <Moon className="absolute h-5 w-5 rotate-90 scale-0 transition-all dark:rotate-0 dark:scale-100" />
+      <span className="sr-only">Toggle theme</span>
+    </Button>
+  );
+}