Add D2 diagram support to documentation

[jumski]

Integrates D2 diagramming tool into the website build pipeline, enabling architecture diagrams directly in MDX files.

Changes

• Added astro-d2 integration with pgflow brand colors for light/dark themes
• Created .github/actions/setup-d2 - reusable action to install D2 CLI with retry logic
• Updated CI workflow to install D2 before building website
• Added public/d2/ to gitignore - SVGs are generated at build time

How it works

Write D2 diagrams in MDX files using ````d2` code blocks:

direction: down
worker: "Edge Worker" {
  shape: cloud
}

At build time:

1. astro-d2 renders diagrams to SVG in public/d2/
2. Code blocks are replaced with <img> tags
3. Static assets deploy to Cloudflare Pages

Example

See /concepts/how-pgflow-works/ for live diagrams showing the three-layer architecture.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 689397e

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[jumski]

• Add D2 diagram support to documentation  #241 👈 (View in Graphite)
• main

---

How to use the Graphite Merge Queue

Add either label to this PR to merge it via the merge queue:

• merge:queue - adds this PR to the back of the merge queue
• hotfix:queue - for urgent hot fixes, skip the queue and merge this PR next

You must have a Graphite account in order to use the merge queue. Sign up using this link.

An organization admin has enabled the Graphite Merge Queue in this repository.

Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.

This stack of pull requests is managed by Graphite. Learn more about stacking.

[nx-cloud]

🤖 Nx Cloud AI Fix Eligible

An automatically generated fix could have helped fix failing tasks for this run, but Self-healing CI is disabled for this workspace. Visit workspace settings to enable it and get automatic fixes in future runs.

_{To disable these notifications, a workspace admin can disable them in workspace settings.}

---

View your CI Pipeline Execution ↗ for commit 689397e

Command	Status	Duration	Result
nx affected -t build --configuration=production...	❌ Failed	25s	View ↗
nx affected -t lint typecheck test --parallel -...	✅ Succeeded	7m 26s	View ↗

---

☁️ Nx Cloud last updated this comment at 2025-10-19 20:27:31 UTC

[github-actions]

🔍 Preview Deployment: Website

✅ Deployment successful!

🔗 Preview URL: https://pr-241.pgflow.pages.dev

📝 Details:

• Branch: setup-d2-diagrams
• Commit: 71b3ec28a995fbc5ed646a9832796b18de203527
• View Logs

_Last updated: _

[github-actions]

🔍 Preview Deployment: Playground

✅ Deployment successful!

🔗 Preview URL: https://pr-241--pgflow-demo.netlify.app

📝 Details:

• Branch: setup-d2-diagrams
• Commit: 71b3ec28a995fbc5ed646a9832796b18de203527
• View Logs

_Last updated: _