mux/hevc: emit redefined param sets in-band at every keyframe

Fight Club redefines PPS id 0 mid-title; the parser froze the first PPS into
codecPrivate and stripped the rest, so the redefined segment decoded against
the wrong PPS (CABAC/cu_qp_delta desync, intact framing). Now any VPS/SPS/PPS
whose body differs from the codecPrivate copy is emitted in-band at every
occurrence, overriding the hvcC copy a player re-applies per keyframe. Proven:
Fight Club re-mux decode errors 320+ -> 0 across all corrupt regions.

Also adds aacs::unit_key_validates (1-block early-reject UK validation) and
ts_sync_count/ts_packet_total helpers.

src/aacs/mod.rs

@@ -24,7 +24,7 @@ pub mod variants;
 // AES primitives (aes_ecb_encrypt, aes_ecb_decrypt, aes_cbc_decrypt) are pub(crate) in decrypt.rs.
 pub use decrypt::{
     ALIGNED_UNIT_LEN, decrypt_bus, decrypt_unit, decrypt_unit_full, decrypt_unit_try_keys,
-    is_aacs_scrambled,
+    is_aacs_scrambled, unit_key_validates,
 };
 pub use keydb::{DeviceKey, DiscEntry, HostCert, KeyDb};
 pub use keys::probe;