Fix proxyFetch is not defined error in zip upload template

The zip.html template is a standalone page that doesn't extend base.html,
so it was missing the proxyFetch function definition needed for chunked
uploads. Added the SCRIPT_ROOT variable and proxyFetch/buildUrl helper
functions directly to the template to support proxy-aware URL generation.

app/templates/upload/zip.html

@@ -126,6 +126,35 @@
         }
     </style>
     <script>
+        // Get the script root from Flask (includes X-Forwarded-Prefix if behind proxy)
+        const SCRIPT_ROOT = {{ request.script_root | tojson | safe }};
+        
+        /**
+         * Build a URL with the correct proxy prefix
+         * @param {string} path - The path to append (e.g., '/api/dashboard-data')
+         * @returns {string} The full URL with proxy prefix
+         */
+        function buildUrl(path) {
+            // Ensure path starts with /
+            if (!path.startsWith('/')) {
+                path = '/' + path;
+            }
+            // Remove leading slash from script_root if present
+            const root = SCRIPT_ROOT.startsWith('/') ? SCRIPT_ROOT.slice(1) : SCRIPT_ROOT;
+            // Combine script root and path
+            return '/' + root + path;
+        }
+        
+        /**
+         * Make a fetch request with proxy-aware URL
+         * @param {string} path - The API path
+         * @param {object} options - Fetch options
+         * @returns {Promise} Fetch promise
+         */
+        function proxyFetch(path, options = {}) {
+            return fetch(buildUrl(path), options);
+        }
+        
         const CHUNK_SIZE = 1024 * 1024; // 1MB chunks
 
         function uploadFileInChunks(file, matchId) {