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.

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Latest commit: a269e7e

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[jumski]

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

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[nx-cloud]

View your CI Pipeline Execution ↗ for commit a269e7e

Command	Status	Duration	Result
nx affected -t verify-exports --base=origin/mai...	✅ Succeeded	4s	View ↗
nx affected -t build --configuration=production...	✅ Succeeded	30s	View ↗
nx affected -t lint typecheck test --parallel -...	✅ Succeeded	5m 10s	View ↗
nx affected -t test:e2e --parallel --base=origi...	✅ Succeeded	4m 16s	View ↗

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☁️ Nx Cloud last updated this comment at 2025-11-27 15:48:30 UTC

[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: _

[github-actions]

🔍 Preview Deployment: Website

✅ Deployment successful!

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

📝 Details:

• Branch: setup-d2-diagrams
• Commit: 6152bb673aee4ca86d9b8d701c2e62205eccd3ab
• View Logs

_Last updated: _