Make IEventSerializer AOT-compatible

[alexeyzimarev]

Summary

• Remove [RequiresUnreferencedCode] and [RequiresDynamicCode] from IEventSerializer interface and all 43 consumer files across core and integration packages
• Extract reflection-based DefaultEventSerializer to new Eventuous.Serialization.Json package (intentionally not AOT-compatible)
• Add EventSerializer static holder class replacing DefaultEventSerializer.Instance / SetDefaultSerializer()
• DefaultStaticEventSerializer and core serialization interface are now fully AOT-clean with zero suppression attributes

Breaking changes

• DefaultEventSerializer moved from Eventuous.Serialization to Eventuous.Serialization.Json package
• DefaultEventSerializer.Instance replaced by EventSerializer.Default
• DefaultEventSerializer.SetDefaultSerializer() replaced by EventSerializer.SetDefault()
• Apps must explicitly configure a serializer (either DefaultStaticEventSerializer for AOT or DefaultEventSerializer from the new package)

Test plan

• Full solution builds with zero errors (from this change)
• Core tests pass (26/26)
• Application tests pass (21/21)
• Subscription tests pass (30/30)
• DI extension tests pass (3/3)
• Integration tests with infrastructure (require docker services)

🤖 Generated with Claude Code