refactor: migrate middleware.ts to proxy.ts (Next.js 16)

Renamed middleware convention to proxy as per Next.js 16 deprecation warning.
- Renamed src/middleware.ts to src/proxy.ts
- Renamed exported function from middleware() to proxy()

src/proxy.ts

@@ -0,0 +1,56 @@
+import { NextResponse } from 'next/server';
+import type { NextRequest } from 'next/server';
+
+export function proxy(request: NextRequest) {
+    // Define public paths that don't require authentication
+    const publicPaths = [
+        '/login',
+        '/api/auth/login',
+        '/_next',
+        '/favicon.ico',
+        '/manifest.json',
+    ];
+
+    const path = request.nextUrl.pathname;
+
+    // Check if the path is public
+    // We use startsWith to cover subpaths if necessary, but strictly usually better for pages
+    // For _next, startsWith is correct. For /login, exact match is better unless we have nested public routes.
+    // Let's use exact match for explicit pages and startsWith for assets/api
+    const isPublicPath =
+        path === '/login' ||
+        path === '/api/auth/login' ||
+        path === '/favicon.ico' ||
+        path === '/manifest.json' ||
+        path.startsWith('/_next');
+
+    // Check for auth token
+    const authToken = request.cookies.get('auth-token');
+
+    // If validated (has token) and trying to access login, redirect to home
+    if (authToken && path === '/login') {
+        return NextResponse.redirect(new URL('/', request.url));
+    }
+
+    // If protected and no token, redirect to login
+    if (!isPublicPath && !authToken) {
+        const loginUrl = new URL('/login', request.url);
+        // loginUrl.searchParams.set('from', path); // We can implement return url later
+        return NextResponse.redirect(loginUrl);
+    }
+
+    return NextResponse.next();
+}
+
+export const config = {
+    matcher: [
+        /*
+         * Match all request paths except for the ones starting with:
+         * - api (API routes, except auth/login which is handled inside middleware)
+         * - _next/static (static files)
+         * - _next/image (image optimization files)
+         * - favicon.ico (favicon file)
+         */
+        '/((?!_next/static|_next/image|favicon.ico).*)',
+    ],
+};