[tjXJNOOBIE]

Refactors CustomEnum around the intended low-level enum model:

• custom-enum families declare typed constants once with register(...)
• identity equality and enum-style name() / ordinal() semantics
• exact valueOf(type, name) lookup and ordered immutable values(type) snapshots
• duplicate names rejected within a concrete type
• removes the public registry/bootstrap/alias/freeze abstraction
• moves EnumValues to its own top-level package-private class
• replaces registry-centric tests with enum-behavior tests
• rewrites the README around a simple ThreadType example
• updates Gradle/project/package publication metadata for tavall-custom-enum-java

Local javac -Xlint:all -Werror smoke validation passed before opening this PR.