feat(trace): Only allow zip files to be selected for upload (#37905)

Author: cpAdm

docs/src/trace-viewer.md

@@ -39,7 +39,7 @@ pwsh bin/Debug/netX/playwright.ps1 show-trace trace.zip
 
 ### Using [trace.playwright.dev](https://trace.playwright.dev)
 
-[trace.playwright.dev](https://trace.playwright.dev) is a statically hosted variant of the Trace Viewer. You can upload trace files using drag and drop or via the `Select file(s)` button.
+[trace.playwright.dev](https://trace.playwright.dev) is a statically hosted variant of the Trace Viewer. You can upload a trace file using drag and drop or via the `Select file` button.
 
 Trace Viewer loads the trace entirely in your browser and does not transmit any data externally.
 

packages/trace-viewer/src/ui/workbenchLoader.tsx

@@ -215,7 +215,7 @@ export const WorkbenchLoader: React.FunctionComponent<{
         input.type = 'file';
         input.click();
         input.addEventListener('change', e => handleFileInputChange(e));
-      }} type='button'>Select file(s)</button>
+      }} type='button'>Select file</button>
       <div style={{ maxWidth: 400 }}>Playwright Trace Viewer is a Progressive Web App, it does not send your trace anywhere,
         it opens it locally.</div>
     </div>}