Named union picker omits Value for nullable custom value type

[HavenDV]

Reproduction

Anthropic regeneration PR tryAGI/Anthropic#295 fails its newly restored PR build in run 36287263480 (attempt 2):

Generated/Anthropic.Models.BetaManagedAgentsModelParams.g.cs(45,89): error CS0266: Cannot implicitly convert type 'Anthropic.BetaManagedAgentsModel?' to 'Anthropic.BetaManagedAgentsModel'.

PickBetaManagedAgentsModel() returns the nullable value-type property with ! rather than extracting .Value. The same regenerated PR also removes .Value from the matching System.Text.Json converter. The generator's HasNullableValueVariant(TypeData) in Sources.Models.AnyOf.cs requires IsAnyOfLike, IsEnum, a built-in primitive, or a global::System.* name even when TypeData.IsValueType is true; this custom enum/value type misses those branches.

Expected

Generated named-union pickers and serializers compile for every nullable value-type variant. Add a focused generator regression test with a custom value-type variant, then regenerate Anthropic and validate build and trim. Do not hand-edit Generated/.

[HavenDV]

Fixed in AutoSDK bccfb04. Anthropic PR #295 regenerated the affected picker and converter, passed build/trimming, merged, and its Publish workflow succeeded.