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.

tests/passn_handler_ab.rs

@@ -84,8 +84,11 @@ struct ScriptedSectorReader {
     trace: Arc<Mutex<Vec<(u32, u16, bool)>>>,
 }
 
+/// A `ScriptedSectorReader` plus the handle recording its `(lba, count, ok)` trace.
+type ScriptedHarness = (ScriptedSectorReader, Arc<Mutex<Vec<(u32, u16, bool)>>>);
+
 impl ScriptedSectorReader {
-    fn new(capacity: u32) -> (Self, Arc<Mutex<Vec<(u32, u16, bool)>>>) {
+    fn new(capacity: u32) -> ScriptedHarness {
         let trace = Arc::new(Mutex::new(Vec::new()));
         (
             Self {