mux: fix non-monotonic audio DTS (TrueHD + DTS-HD MA) and stamp builds with git hash

TrueHD: when the PES PTS lags the access-unit cadence, resync to the PTS
but never snap the running timestamp backward, so the emitted DTS stays
monotonic across the resync (next_pts_ns = max(next_pts_ns, pts)).

DTS-HD MA: size each EXSS extension substream exactly from its header
(exss_frame_size) and skip it as a unit, so a false 0x7FFE8001 core sync
inside the lossless extension payload can no longer split the access unit
and truncate the extension. Falls back to a bounded scan when the header
is unparseable.

Provenance: build.rs bakes the git short hash into GIT_SUFFIX; the muxing/
writing-application field and the FVI generator tag now record the exact
build (e.g. "freemkv 1.1.0-beta.1 (g835cc99)"), so any output file is
traceable to the revision that produced it.

src/mux/videomap.rs

@@ -37,7 +37,7 @@ pub const FVI_VERSION: u32 = 1;
 
 /// Producing tool tag for the header `"generator"` member
 /// (`docs/FVI_FORMAT.md` §6).
-pub const FVI_GENERATOR: &str = concat!("freemkv/", env!("CARGO_PKG_VERSION"));
+pub const FVI_GENERATOR: &str = concat!("freemkv/", env!("CARGO_PKG_VERSION"), env!("GIT_SUFFIX"));
 
 /// Header `"timescale"` for all `pts`/`dts` ticks (`docs/FVI_FORMAT.md` §10).
 /// The highway carries presentation timestamps in nanoseconds, so the timescale