Add generic hasher traits and KDF core for cross-platform crypto

[mamonet]

Add generic hasher traits and a KDF core module to enable code sharing between keetanetwork-crypto and the Ledger device application.

• Create hash_trait.rs with Sha3_256Hasher trait
• Create kdf_core.rs with generic HMAC-SHA3-256, HKDF, and key derivation
• Update Cargo.toml with new feature flags structure
• Add comprehensive tests for the generic core
• Refactor hash.rs and kdf.rs to delegate to generic core