F-3340: AesGcmStream.final decrypt path passed len(authTag) straight to
wc_AesGcmDecryptFinal, letting a caller truncate the verification window
(forgery probability ~2^-32 instead of 2^-128 for a 4-byte tag against a
16-byte configuration). Reject len(authTag) != self._tag_bytes and pass
self._tag_bytes to wolfSSL, mirroring ChaCha20Poly1305.decrypt. Added
test_decrypt_rejects_wrong_tag_length. Also fixed test_encrypt_short_tag
which was relying on the bug (decrypt side defaulted to tag_bytes=16
against a 12-byte tag).
F-3089: Declare label as const byte* in the wc_RsaPublicEncrypt_ex and
wc_RsaPrivateDecrypt_ex cdefs so CFFI can accept Python bytes without
exposing a writable pointer into immutable memory. wolfSSL does not
modify label.
F-3090: Declare nonce as const byte* in the wc_InitRngNonce and
wc_InitRngNonce_ex cdefs for the same reason.
F-1983, F-1984: Add minimum + upper bounds to requirements/{prod,test,
docs}.txt so a hijacked release of cffi, tox, pytest, types-cffi,
Sphinx, or sphinx_rtd_theme does not get pulled silently on the next
pip install. setup.txt resolves transitively via prod.txt.
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