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: 2314aae

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[jumski]

• refactor: remove unused mermaid diagrams and scripts #535
• Add D2 diagram support to documentation  #241 👈 (View in Graphite)
• main

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

[nx-cloud]

View your CI Pipeline Execution ↗ for commit 2314aae

Command	Status	Duration	Result
nx run edge-worker:test:integration	✅ Succeeded	5m 17s	View ↗
nx run client:e2e	✅ Succeeded	2m 50s	View ↗
nx affected -t verify-exports --base=origin/mai...	✅ Succeeded	3s	View ↗
nx affected -t build --configuration=production...	✅ Succeeded	3s	View ↗
nx affected -t lint typecheck test --parallel -...	✅ Succeeded	1m 49s	View ↗
nx run core:pgtap	✅ Succeeded	1m 33s	View ↗
nx run cli:e2e	✅ Succeeded	5s	View ↗
nx run edge-worker:e2e	✅ Succeeded	29s	View ↗

---

☁️ Nx Cloud last updated this comment at 2025-12-10 12:00:54 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: e423520cc6cc44dd0ab04b89e5a3b0363a5b0023
• View Logs

_Last updated: _

[jumski]

Merge activity

• Dec 10, 12:24 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Dec 10, 12:24 PM UTC: @jumski merged this pull request with Graphite.