1.2.0: mux loss-concealment read path (P3/Edit-2, A2 NULL-TS fill)

Decrypt-verify is a RIP gate, not a MUX gate. On the mux read path an
undecryptable content unit must never abort the mux:

- DecryptingSectorSource gains tolerate_decrypt_loss(): when set, an
  undecryptable in-content unit is tallied, overwritten with valid NULL
  TS packets (PID 0x1FFF) via aacs::fill_null_ts_unit, logged loud with
  its LBA, and the read returns Ok — the stream keeps flowing. The rip
  paths keep the fail-loud DECRYPT_VERIFY_READ decorator (re-read off the
  disc); only the mux opts in.
- Wire it into both mux read paths: the file-backed highway
  (build_iso_pipeline) and the inline DiscStream.
- NULL-TS fill keeps the demuxer byte-synced on the 192-byte stride; the
  lost video/audio PID packets surface as a CC gap the TS assembler
  already drops a partial PES on (the B1 foundation). Ciphertext is never
  passed downstream either way.
- Fix stale resolve_vid_only no-cert test: default is UHD (audit #4).

Tests: conceal-as-NULL-TS, fill well-formedness, fail-loud still holds.

src/mux/resolve.rs

@@ -629,8 +629,13 @@ pub fn build_iso_pipeline<S: SectorSource + Send + 'static>(
         crate::decrypt::DecryptKeys::Aacs { .. } => 3,
         _ => 1,
     };
+    // MUX path: tolerate decrypt loss. An undecryptable content unit is concealed
+    // (NULL TS fill) + tallied + logged, never an abort — decrypt-verify is a RIP
+    // gate, not a mux gate (P3). The rip's own read paths keep their fail-loud
+    // decorator; only this mux pipeline opts in.
     let mut decrypting =
-        crate::sector::DecryptingSectorSource::new(Box::new(reader) as Box<dyn SectorSource>, keys);
+        crate::sector::DecryptingSectorSource::new(Box::new(reader) as Box<dyn SectorSource>, keys)
+            .tolerate_decrypt_loss();
     // Install the fresh-key-on-failure callback (if any) so a unit no held key
     // decrypts is re-tried via the application's key source before being counted
     // as loss.