feat: add dynamic attribute support for self-referential schemas

[claude]

Requested by Brady Burke · Slack thread

Before / After

Before: This fork of terraform-plugin-codegen-framework had no support for the dynamic attribute type. Feeding it a provider-code-spec that contained a dynamic attribute would fail with attribute type not defined, because there was no generator wired up for it.

After: The framework recognizes dynamic attributes in the spec and generates the corresponding schema.DynamicAttribute{...} plus the matching types.Dynamic model field, for resources, data sources, and providers. This lets the generator consume specs that represent a self-referential schema edge as a dynamic attribute (see the companion OpenAPI-codegen PR linked below) and emit compiling Go provider code.

How

• New GeneratorDynamicAttribute in internal/resource, internal/datasource, and internal/provider, mirroring the existing scalar (bool) generators: Schema() emits schema.DynamicAttribute{...}, ModelField() emits a types.Dynamic field, plus Imports, Equal, AttrType/AttrValue.
• Dispatch: added an a.Dynamic != nil case to NewAttribute in each of the three convert.go files.
• Supporting wiring: GeneratorDynamicAttribute value added to the schema.Type enum, DynamicValueType = "types.Dynamic" added to internal/model, and Dynamic entries added to the PlanModifierType / ValidatorType enums so custom plan modifiers/validators for dynamic attributes resolve correctly.
• Regression tests for the resource generator (New, Schema, ModelField).

Known scope limit: AssociatedExternalType/custom-type rendering and spec-level default for dynamic attributes are not emitted (the upstream self-referential use case never sets them); this can be extended later if needed.

Cross-dependency

This PR pairs with the OpenAPI-codegen change that first emits dynamic attributes for self-referential schemas — companion PR: starburstdata/terraform-plugin-codegen-openapi#2. Both are required for the end-to-end codegen pipeline to succeed on the recursive ingest_column schema.

go build ./... and go test ./internal/... pass (including the new dynamic tests; the existing golden-file internal/cmd tests are unaffected).

---

Generated by Claude Code