feat: implement dynamic API proxying to FastAPI backend

- Added a new route handler for dynamic API requests, allowing proxying to the FastAPI backend.
- Removed the previous rewrite configuration in next.config.ts for cleaner integration.
- Updated .env.example to clarify backend URL usage.

surfsense_web/next.config.ts

@@ -44,21 +44,6 @@ const nextConfig: NextConfig = {
 		},
 	},
 
-	// Proxy /api/v1/* to the FastAPI backend. Keeps the real backend host
-	// out of the client bundle. FASTAPI_BACKEND_INTERNAL_URL is server-only.
-	async rewrites() {
-		const target =
-			process.env.FASTAPI_BACKEND_INTERNAL_URL ||
-			process.env.NEXT_PUBLIC_FASTAPI_BACKEND_URL ||
-			"http://localhost:8000";
-		return [
-			{
-				source: "/api/v1/:path*",
-				destination: `${target.replace(/\/+$/, "")}/api/v1/:path*`,
-			},
-		];
-	},
-
 	// Configure webpack (SVGR)
 	webpack: (config) => {
 		// SVGR: import *.svg as React components