fix(maps): avoid 404 on keyless Google tiles-token probe (#1066)

Return an uncached unavailable-token response for keyless Google tile-token requests.

Contribution by @dvilrgamerz.

server/standalone/google-token-unavailable.js

@@ -0,0 +1,27 @@
+/**
+ * Treat an unavailable Google Maps tile-token endpoint as a supported, silent
+ * outcome. Install after real token providers and before the unknown-API 404.
+ */
+export function googleTokenUnavailablePlugin() {
+  const install = (server) => {
+    server.middlewares.use((req, res, next) => {
+      const pathname = String(req.url || '').split('?')[0];
+      if (
+        (req.method !== 'GET' && req.method !== 'HEAD') ||
+        pathname !== '/api/google/tiles-token'
+      ) {
+        next();
+        return;
+      }
+
+      res.writeHead(204, { 'Cache-Control': 'no-store' });
+      res.end();
+    });
+  };
+
+  return {
+    name: 'google-token-unavailable',
+    configureServer: install,
+    configurePreviewServer: install,
+  };
+}