Preserve Java enum semantics for explicit java.lang.Enum inheritance

[zielinsky]

Scala currently accepts some explicit java.lang.Enum[...] usages that are not consistent with Java enum semantics. In particular, F-bound checking alone is not sufficient here: it can accept programs where the type argument satisfies E <: Enum[E], but does not actually match the enum class.

This leads to problematic cases such as enum E extends Enum[Nothing] { case X } (i11252)

These cases may compile, but can break the expected Java enum behavior, especially around reflection and runtime consistency.

After discussion during the Scala Core meeting (01.04.2026), we decided that when code explicitly uses extends java.lang.Enum[...], Scala should preserve Java enum semantics more strictly.

This means we require:

1. the java.lang.Enum type argument to refer to the enum class itself
2. the enum to have no type parameters

This rejects examples such as:

• enum E extends Enum[Nothing]
• generic enums like enum E[A] extends Enum[E[?]]

Fixes #11252
Fixes #11253

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Typo in the error message has also been fixed (paramerized -> parameterized)