[AS-322] Blog draft: Coprocessors and A/B testing

[ilan-bel]

Summary

Adds docs/blog-draft-coprocessors-ab-testing.md — a publishable-shape blog post draft showing how to use a Router coprocessor as an experimentation control plane (deterministic per-user bucketing, subgraph routing override, telemetry/Studio observability).

Includes editorial notes at the bottom calling out:

• Final destination: apollographql.com/blog (the ticket asked for a blog post, but Marketing/DevRel owns publish).
• The traffic_shaping.rules block in the draft is illustrative; reconcile against the actual Router config surface before publishing.
• Companion code: recommend a small PR against apollosolutions/coprocessor-examples adding an ab-testing/ directory.

Tracks AS-322.

Test plan

• Editorial review for tone/length
• Verify Router config block against current Router release
• Companion code repo PR opened against apollosolutions/coprocessor-examples

🤖 Generated with Claude Code

[ilan-bel]

@andywgarcia Assigning to you — this blog draft (AS-322: Coprocessors and A/B testing) has no reviews yet. Can you take it, find a reviewer, or let me know if it should be deprioritized?