Jetpack AI: Add suggest-guidelines proxy endpoint (FORNO-186)

[aagam-shah]

Summary

Adds a proxy endpoint at /wpcom/v2/jetpack-ai/suggest-guidelines that forwards guideline generation requests for AI-powered content guidelines. Supports content filters (authors, categories) with extensible structure.

Files changed

• projects/plugins/jetpack/_inc/lib/core-api/wpcom-endpoints/class-wpcom-rest-api-v2-endpoint-agent-guidelines-ai.php — Proxy endpoint

Test plan

TBA

[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 (Jetpack), and enable the forno-186-build-site-content-aggregation-pipeline-for-guideline branch.
• To test on Simple, run the following command on your sandbox:

bin/jetpack-downloader test jetpack forno-186-build-site-content-aggregation-pipeline-for-guideline

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:

• ✅ Include a description of your PR changes.
  
• 🔴 Add a "[Status]" label (In Progress, Needs Review, ...).
  
• 🔴 Add testing instructions.
  
• 🔴 Specify whether this PR includes any changes to data or privacy.
  
• 🔴 Add changelog entries to affected projects
  

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 🤖

---

🔴 Action required: Please include detailed testing steps, explaining how to test your change, like so:

## Testing instructions:

* Go to '..'
*

---

🔴 Action required: We would recommend that you add a section to the PR description to specify whether this PR includes any changes to data or privacy, like so:

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

My PR adds *x* and *y*.

---

🔴 Action required: Please add missing changelog entries for the following projects: projects/plugins/jetpack

Use the Jetpack CLI tool to generate changelog entries by running the following command: jetpack changelog add.
Guidelines: /docs/writing-a-good-changelog-entry.md

---

Follow this PR Review Process:

1. Ensure all required checks appearing at the bottom of this PR are passing.
2. Make sure to test your changes on all platforms that it applies to. You're responsible for the quality of the code you ship.
3. You can use GitHub's Reviewers functionality to request a review.
4. When it's reviewed and merged, you will be pinged in Slack to deploy the changes to WordPress.com simple once the build is done.

If you have questions about anything, reach out in #jetpack-developers for guidance!

[jp-launch-control]

Code Coverage Summary

1 file is newly checked for coverage.

File	Coverage
projects/plugins/jetpack/_inc/lib/core-api/wpcom-endpoints/class-wpcom-rest-api-v2-endpoint-agent-guidelines-ai.php	0/86 (0.00%) 💔

Full summary · PHP report · JS report

_{If appropriate, add one of these labels to override the failing coverage check: Covered by non-unit tests Use to ignore the Code coverage requirement check when E2Es or other non-unit tests cover the code Coverage tests to be added later Use to ignore the Code coverage requirement check when tests will be added in a follow-up PR I don't care about code coverage for this PR Use this label to ignore the check for insufficient code coveage.}