[ounsworth]

(this is a refactor of #167 onto release/0.1.3alpha after #133 was merged)

The core problem being solved here is that when a symmetric cipher algorithm simply requires a key: &KeyMaterial<N>, then nothing is preventing you from, for example, using the same key for AES_128_CBC and Ascon_AEAD128.

This PR adds per-algorithm key types, such as AES_128_CBC_Key and Ascon_AEAD128_Key so that cross-algorithm key re-use can be detected and blocked at compile-time.

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Claude-generated PR description:

Each symmetric cipher instantiation carries its own key type, so a key made for one algorithm cannot be used with another: a new public trait SymmetricCipherKey<KEY_LEN>, a shallow wrapper over KeyMaterial<KEY_LEN> that carries the algorithm's key policy, and a generic parameter K: SymmetricCipherKey<KEY_LEN> threaded through the cipher traits and every mode in bouncycastle-cipher. Each alias gets its key type (AES_CBC_128_Key, AES_GCM_256_Key, Ascon_AEAD128_Key, ...).

This is PR #167 (02b852b) re-applied to release/0.1.3alpha as one commit. #167 was written against feature/simple-ciphers at 20b9051; release has since taken the rest of that branch (PR #133), so the change is ported onto it:

• Ascon: the key type goes onto release's Ascon_AEAD128 struct; SymmetricCipherKey: dedicated key types per algorithm #167's changes to the removed AsconAead128 wrappers and inherent API are dropped. Resume no longer re-checks the key, since a typed key has passed the policy when it was made. Suspended-state layout is unchanged.
• API added on release after 20b9051 now takes &K as well: the AEADCipherEncryptor *_nonce methods, CCM's one-shot and trait-pair impls, GCM's do_encrypt_init_nonce.
• The toy block cipher lives in crypto/cipher/tests/common on release; ToyCipherKey is ported there, and the tests/modes toys and the ctr_key_stream unit tests share one inclusion of it. core-test-framework drops the bouncycastle-rng dependency SymmetricCipherKey: dedicated key types per algorithm #167 added for the toy.
• Tests and benches that release reorganised get SymmetricCipherKey: dedicated key types per algorithm #167's change in their new form: padded_alias_tests.rs and alias_tests.rs (for cbc_/ecb_alias_tests.rs), the suspend-test macro, the de-duplicated aes_modes_benches, alg_name_tests, the mem-usage benches.
• SymmetricCipherKey: dedicated key types per algorithm #167's ECB-based rewrites of fips197_tests, sp800_38a_ecb_tests and ecb_bc-test-data use release's modes::hazmat::ecb::Ecb path, ModeNames bound and do_*_blocks_inplace.
• aes_benches.rs is deleted as in SymmetricCipherKey: dedicated key types per algorithm #167; the aes_modes_benches docs no longer refer to it.

Assisted-by: Claude:claude-fable-5-1
Assisted-by: Claude:claude-opus-5-5