AACS pipeline reshape + TrueHD metadata + central consts + clippy/fmt clean

- AACS: delete in-lib keydb parser (Step 3); boil-down primitives
  (mk_from_dk/vuk_from_mk/uk_from_vuk) + newtypes; KeySource->get_uk(ctx)+
  ResolveCtx; Unlocker->unlock()->Result<Vid,UnlockError> + AacsCertUnlocker;
  OEM bus-key gate (AacsBusKeyUnavailable); structured ResolutionTrace (Step 4).
- TrueHD: sample-rate from major-sync, Atmos label, 44.1k AU duration.
- consts: central media/format constants module; 17 duplicate const-defs
  centralized (sector/TS-packet/source-packet); mpls stream-entry + category
  codes named.
- clippy --all-targets -D warnings clean (1.86); fmt clean; 2199 lib tests.

src/diag.rs

@@ -116,7 +116,9 @@ pub fn sample_rate_hz(s: SampleRate) -> u32 {
     match s {
         SampleRate::S44_1 => 44100,
         SampleRate::S48 => 48000,
+        SampleRate::S88_2 => 88200,
         SampleRate::S96 => 96000,
+        SampleRate::S176_4 => 176400,
         SampleRate::S192 => 192000,
         SampleRate::S48_96 => 96000,
         SampleRate::S48_192 => 192000,