feat(probe): record and print the footage stream inventory

FootageBehavior now keeps the probed stream list (video/audio, per-stream
duration in rationals) instead of dropping it, and the probe CLI walks
that inventory to report real durations, frame rates and stream counts
rather than the previous zero placeholders.

crates/oak-cli/tests/cli.rs

@@ -189,12 +189,15 @@ fn probe_on_the_media_fixture_prints_streams() {
 	let (code, stdout, stderr) = run(&["probe", media.to_str().unwrap()]);
 	assert_eq!(code, 0, "stderr: {stderr}");
 	// tests/demo.mp4 through the engine: the probe records the ffmpeg
-	// decoder; the stream descriptions are dropped by the module today,
-	// so the counts/duration report 0 — the pinned engine contract.
+	// decoder and the full stream inventory (1920x1080 @ 25 fps video,
+	// 48 kHz stereo audio, 17 s each).
 	assert!(stdout.contains("Decoder: ffmpeg"), "{stdout}");
-	assert!(stdout.contains("Duration: 0.000000 s"), "{stdout}");
-	assert!(stdout.contains("Video streams: 0"), "{stdout}");
-	assert!(stdout.contains("Audio streams: 0"), "{stdout}");
+	assert!(stdout.contains("Duration: 17.000000 s"), "{stdout}");
+	assert!(stdout.contains("Video streams: 1"), "{stdout}");
+	assert!(stdout.contains("1920x1080"), "{stdout}");
+	assert!(stdout.contains("25/1 fps"), "{stdout}");
+	assert!(stdout.contains("Audio streams: 1"), "{stdout}");
+	assert!(stdout.contains("48000 Hz, 2 channels"), "{stdout}");
 	assert!(stdout.contains("Subtitle streams: 0"), "{stdout}");
 }