wpcomsh: bilmur: Add site timezone to tag

[mreishus]

Fixes #

Proposed changes:

• Updates the Bilmur Real User Monitoring (RUM) library to include the site’s timezone.
• Adds a new function wpcomsh_stats_timezone_string() to standardize timezone output (e.g., converts +05:30 to Asia/Kolkata or Etc/GMT+5).
• Injects the timezone as a data-site-tz attribute in the Bilmur <script> tag.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

Does this pull request change what data or activity we track or use?

Yes, this PR adds the site’s timezone to the data sent to Bilmur for performance tracking. This could indirectly reveal location info (e.g., America/New_York), but it’s site-level, not user-level data.

Testing instructions:

• Make a WoA dev site, download Jetpack Beta, install it and switch wpcom site helper to this branch as explained in the comment below
• Open the site in a browser and inspect the page source (Ctrl+U or right-click > View Source).
• Look for the <script id="bilmur" ...> tag in the footer.
• Check that it includes a data-site-tz attribute (e.g., data-site-tz="Etc/GMT+0" or a city like Asia/Kolkata).
• Change the site’s timezone in WordPress (Settings > General > Timezone) to something else (e.g., UTC+5:30 or New York), reload, and verify the data-site-tz updates accordingly.

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WoA dev site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin (WordPress.com Site Helper), and enable the update/wpcomsh-bilmur-tz branch.

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

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This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

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The e2e test report can be found here. Please note that it can take a few minutes after the e2e tests checks are complete for the report to be available.

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Wpcomsh plugin:

• Next scheduled release: Atomic deploys happen twice daily on weekdays (p9o2xV-2EN-p2).

If you have any questions about the release process, please ask in the #jetpack-releases channel on Slack.

[jp-launch-control]

Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/plugins/wpcomsh/wpcomsh.php	83/313 (26.52%)	2.77%	2 ❤️‍🩹

Full summary · PHP report

[mreishus]

Tested on a WoA dev site:

<script defer id="bilmur" data-customproperties="{&quot;woo_active&quot;:&quot;0&quot;}" data-provider="wordpress.com" data-service="atomic"  src="https://s0.wp.com/wp-content/js/bilmur.min.js?m=202508" data-site-tz="America/Chicago"></script>