feat(probe): ffprobe wrapper

Post-download truth for DESIGN.md §5.6: resolution, codec, HDR with the
Dolby Vision profile as a number, per-track audio language plus the title
and handler_name strings §5.2 needs, subtitles, duration and size.

Also picks the feature file out of a multi-file torrent — largest video
file, checked against the expected runtime so an extras reel does not get
imported as the film.

The fixture clips are generated by scripts/make-probe-fixtures.sh. The two
Dolby Vision ones splice a dvcC/dvvC box into a real HEVC clip, since x265
will not encode DV without an RPU.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Cargo.lock

@@ -137,6 +137,14 @@ dependencies = [
 [[package]]
 name = "arr-probe"
 version = "0.1.0"
+dependencies = [
+ "arr-core",
+ "serde",
+ "serde_json",
+ "thiserror",
+ "tokio",
+ "tracing",
+]
 
 [[package]]
 name = "assert-json-diff"