docs(plan): Extract starlark infrastructure from pkg/op into pkg/op/bind - #265

Summary

• Plan document for refactor(op): Extract starlark infrastructure from pkg/op into pkg/op/bind #264 — extract starlark binding infrastructure from pkg/op into pkg/op/bind
• Five phases: create plan provider, create bind package, sever starlark refs, update codegen, update consumers
• Key decisions: pkg/op/bind package name, bind.StarlarkRuntime + bind.StarlarkConfig as minimal public API, plan as a provider at pkg/op/provider/plan

Test plan

• Plan reviewed and approved
• Tracking issue refactor(op): Extract starlark infrastructure from pkg/op into pkg/op/bind #264 created