VorbisComments: TRACKNUMBER=`current/total` handling should be under implicit conversions

[Serial-ATA]

The special case for TRACKNUMBER in VorbisComments is an implicit conversion, and it can alter metadata even if it isn't in the current/total form:

lofty-rs/lofty/src/ogg/read.rs

Lines 171 to 203 in 09a9352

	// Support the case of TRACKNUMBER being equal to current/total
	k if k.eq_ignore_ascii_case(b"TRACKNUMBER") => {
	match utf8_decode_str(value) {
	Ok(value) => {
	// try to parse as current/total
	let mut value_split = value.splitn(2, '/');
	let track_number: Option<u32> =
	value_split.next().and_then(|b| b.parse().ok());
	let track_total: Option<u32> =
	value_split.next().and_then(|b| b.parse().ok());
	if let Some(n) = track_number {
	tag.set_track(n);
	} else {
	// Probably some other format, like a vinyl track number (A1, B1, etc.).
	// Just leave it up to the caller to deal with.
	tag.items
	.push((String::from("TRACKNUMBER"), value.to_owned()));
	}
	if let Some(n) = track_total {
	tag.set_track_total(n);
	}
	},
	Err(e) => {
	if parse_mode == ParsingMode::Strict {
	return Err(e);
	}
	log::warn!("Non UTF-8 value found, discarding field {key:?}");
	continue;
	},
	}
	},

Should be skipped if ParseOptions::implicit_conversions is disabled.

Discussed in #539

^{Originally posted by Methapon2001 August 14, 2025}
When I try to get track number and track total, disc and disc total from my FLAC (or other file type) file which should have leading 0, instead I got number with non leading using get or get_string.

I tried with wav file it works as expected.

I tried change probed options(disable implicit conversion / relaxed) and it is not working.

I wonder if this is bug or working as expected.

I tried symphonia it does contains zero leading and also in MusicBrainz Picard.