fix: introduce our own cors proxy for git import to fix 403 errors on isometric git cors proxy (#924)

* Exploration of improving git import

* Fix our own git proxy

* Clean out file counting for progress, does not seem to work well anyways

app/routes/api.git-proxy.$.ts

@@ -0,0 +1,65 @@
+import { json } from '@remix-run/cloudflare';
+import type { ActionFunctionArgs, LoaderFunctionArgs } from '@remix-run/cloudflare';
+
+// Handle all HTTP methods
+export async function action({ request, params }: ActionFunctionArgs) {
+  return handleProxyRequest(request, params['*']);
+}
+
+export async function loader({ request, params }: LoaderFunctionArgs) {
+  return handleProxyRequest(request, params['*']);
+}
+
+async function handleProxyRequest(request: Request, path: string | undefined) {
+  try {
+    if (!path) {
+      return json({ error: 'Invalid proxy URL format' }, { status: 400 });
+    }
+
+    const url = new URL(request.url);
+
+    // Reconstruct the target URL
+    const targetURL = `https://${path}${url.search}`;
+
+    // Forward the request to the target URL
+    const response = await fetch(targetURL, {
+      method: request.method,
+      headers: {
+        ...Object.fromEntries(request.headers),
+
+        // Override host header with the target host
+        host: new URL(targetURL).host,
+      },
+      body: ['GET', 'HEAD'].includes(request.method) ? null : await request.arrayBuffer(),
+    });
+
+    // Create response with CORS headers
+    const corsHeaders = {
+      'Access-Control-Allow-Origin': '*',
+      'Access-Control-Allow-Methods': 'GET, POST, PUT, DELETE, OPTIONS',
+      'Access-Control-Allow-Headers': '*',
+    };
+
+    // Handle preflight requests
+    if (request.method === 'OPTIONS') {
+      return new Response(null, {
+        headers: corsHeaders,
+        status: 204,
+      });
+    }
+
+    // Forward the response with CORS headers
+    const responseHeaders = new Headers(response.headers);
+    Object.entries(corsHeaders).forEach(([key, value]) => {
+      responseHeaders.set(key, value);
+    });
+
+    return new Response(response.body, {
+      status: response.status,
+      headers: responseHeaders,
+    });
+  } catch (error) {
+    console.error('Git proxy error:', error);
+    return json({ error: 'Proxy error' }, { status: 500 });
+  }
+}