fix(trace): convert file path to URI in StdinServer._loadTrace

[li-zhixin]

Summary

Fix trace viewer failing when receiving trace paths via stdin (used by VS Code extension for live trace).

• StdinServer._loadTrace() now calls validateTraceUrl() to convert file paths to file?path= URI format
• This makes stdin path handling consistent with runTraceViewerApp() and runTraceInBrowser()

Problem

After #38566, the trace viewer expects trace URIs in file?path=... format, but StdinServer._loadTrace() was still sending raw file paths. This caused the Service Worker to attempt fetching the raw path directly, resulting in:

Not allowed to load local resource: file:///C:/Users/.../traces/xxx.json

Root Cause

In commit 185bfb7, validateTraceUrl() was updated to convert file paths to URI format, but StdinServer._loadTrace() was not updated to use this function.

Fix

  private _loadTrace(traceUrl: string) {
-   this._traceUrl = traceUrl;
+   const validatedUrl = validateTraceUrl(traceUrl);
+   this._traceUrl = validatedUrl;
    clearTimeout(this._pollTimer);
-   this.sendEvent?.('loadTraceRequested', { traceUrl });
+   this.sendEvent?.('loadTraceRequested', { traceUrl: validatedUrl });
  }

Test Plan

• Verified VS Code extension (v1.1.17) live trace now works with this fix
• Existing trace viewer tests should pass

Fixes #39096

[li-zhixin]

Closing this PR as the fix has been implemented in #39121 by @Skn0tt. Thanks for picking this up! 🙏