Provides an implementation of AshAuthentication.HashProvider using SHA-256.
This is a fast, deterministic hash provider suitable for hashing high-entropy
system-generated values like recovery codes. It is NOT suitable for hashing
user-chosen passwords — use AshAuthentication.BcryptProvider or
AshAuthentication.Argon2Provider for passwords.
Because SHA-256 is fast, inputs must have sufficient entropy to resist offline brute-force attacks. This provider requires a minimum of 60 bits of input entropy (enforced at compile time by the strategy verifier).