refactor(web_core): extract shared Zod schema introspection and metadata utilities

[josemontespg]

Overview

GenericBinder (renderers/web_core/src/v0_9/rendering/generic-binder.ts) and NodeResolver (renderers/web_core/src/v0_9/nodes/ref-fields.ts) both independently inspect Zod schemas:

1. Accessing private _def internals (typeName, innerType, description, options, shape()).
2. Duplicating unwrapping loops for ZodOptional, ZodNullable, ZodDefault, and ZodEffects.
3. Defining duplicate schema reference strings (REF:common_types.json#/$defs/...).

Goals

• Centralize Schema Constants: Export canonical reference constants (CHILD_LIST_REF, COMPONENT_ID_REF, ACTION_REF, DATA_BINDING_REF) from a central location (renderers/web_core/src/v0_9/schema/constants.ts or common-types.ts).
• Shared Schema Introspection Utility: Consolidate unwrapping logic into a dedicated helper module (renderers/web_core/src/v0_9/schema/schema-reflection.ts) so callers avoid accessing _def directly.
• Extend Schema Metadata: Broaden the a2uiChildRef metadata pattern introduced in PR feat(react): render A2uiSurface through the node layer #2393 (markChildRef / childRefKindOf) to Action and Dynamic* schemas (a2uiKind: 'action' | 'dynamic' | 'child-list' | 'component-id').

References

• PR feat(web_core): enhance generic binder schema inference #2359: feat(web_core): enhance generic binder schema inference #2359
• PR feat(react): render A2uiSurface through the node layer #2393: Node layer schema metadata implementation (commit 3a2f5f24)

[wal33d006]

@josemontespg Happy to take this as my first contribution (if the maintainers are okay with external contributions).

generic-binder.ts:64 already has a TODO.
Plan: add schema/schema-reflection.ts with a shared unwrap, export the four REF constants from common-types.ts, and extend markChildRef to a2uiKind covering Action/Dynamic.

Also, should I wait on #2444 ?

[jacobsimionato]

I think that @josemontespg should handle this as it's tightly coupled to his existing work. Thank you very much for your offer though, @wal33d006 !