Stop dropping audiobook releases that are not m4b or mp3 (#1199)

An IRC audiobook search returned nothing while OpenBooks, reading the
same @search answer from the same channel, listed results. Three
separate defects were discarding them.

The audiobook format list was maintained by hand in four places and had
drifted. The settings UI offered only m4b/mp3/m4a/zip/rar, and that list
is the only one a user's config can be built from, so flac, opus, ogg,
aac, wav and wma were unreachable everywhere — even though the IRC
parser recognized them, the IRC sorter ranked them (dead code that could
never fire), archive extraction knew them and Prowlarr searched for
them. A FLAC audiobook was invisible in search and, if it arrived
anyway, rejected after download as "format not supported".
AUDIOBOOK_FORMATS and ARCHIVE_FORMATS now live once in core.utils and
every layer derives from them, which also restored the missing .opus in
the post-download scan's trackable extensions.

Widening the default alone would not have reached anyone already
affected: initialize_default_configs() writes field defaults only when a
tab has no config file yet, so an existing install keeps its persisted
m4b/mp3 list forever. migrate_audiobook_formats rewrites a list that
still matches the old default exactly and leaves every other value
alone — re-enabling formats someone had deliberately turned off would be
worse than leaving them narrow.

The IRC parser filtered by file extension alone. Multi-file audiobooks
ship as a .rar or .zip of MP3s, which matched neither SUPPORTED_FORMATS
nor SUPPORTED_AUDIOBOOK_FORMATS, so they fell out of the ebook bucket
and the audiobook bucket both. Results are now classified before the
format filter is applied: an audio extension means audiobook, an ebook
extension means ebook, and for a container — where the extension says
nothing about the contents — the release name decides. An ebook archive
stays out of audiobook results.

RESULT_LINE_REGEX matched \w+ after any dot, so a line carrying no file
extension parsed as format "5mb" out of "::INFO:: 620.5MB", taking the
title and the size down with it and guaranteeing every downstream filter
dropped it. Any decimal size did this. The extension is now matched
against the known formats, so such a line falls through to the simple
pattern and comes back as "unknown", which the rest of the parser
already handles. ALL_RECOGNIZED_FORMATS became an ordered tuple in the
process: it was a set, so which extension won for a line naming two of
them depended on set iteration order and could vary between restarts.

Refs #1129

tests/core/test_audiobook_format_consistency.py

@@ -0,0 +1,38 @@
+"""The audiobook format list must stay in agreement across every layer that gates on it.
+
+These lists were maintained by hand in four places and drifted: the settings UI offered
+only m4b/mp3/m4a, so FLAC/OPUS/OGG could never be enabled even though the parsers
+recognized them, the sorter ranked them, and archive extraction knew them. The result was
+a FLAC audiobook that was invisible in search and rejected after download. They now all
+derive from `shelfmark.core.utils.AUDIOBOOK_FORMATS`; this test fails if one drifts again.
+"""
+
+from shelfmark.config.settings import _AUDIOBOOK_FORMAT_OPTIONS
+from shelfmark.core.utils import ARCHIVE_FORMATS, AUDIOBOOK_FORMATS
+from shelfmark.download.archive import ALL_AUDIO_EXTENSIONS
+from shelfmark.release_sources.irc import parser
+from shelfmark.release_sources.prowlarr.source import AUDIOBOOK_FORMATS as PROWLARR_FORMATS
+
+
+def test_archive_extraction_knows_every_audiobook_format():
+    assert ALL_AUDIO_EXTENSIONS == {f".{fmt}" for fmt in AUDIOBOOK_FORMATS}
+
+
+def test_prowlarr_knows_every_audiobook_format():
+    assert PROWLARR_FORMATS == list(AUDIOBOOK_FORMATS)
+
+
+def test_irc_parser_knows_every_audiobook_format():
+    assert set(AUDIOBOOK_FORMATS) <= set(parser.ALL_RECOGNIZED_FORMATS)
+
+
+def test_every_audiobook_format_is_selectable_in_settings():
+    """The settings list is the only one a user's config can be built from."""
+    selectable = {option["value"] for option in _AUDIOBOOK_FORMAT_OPTIONS}
+
+    assert selectable == {*AUDIOBOOK_FORMATS, *ARCHIVE_FORMATS}
+
+
+def test_audiobook_and_ebook_formats_do_not_overlap():
+    """Overlap would make content-type classification by extension ambiguous."""
+    assert not set(AUDIOBOOK_FORMATS) & set(parser.EBOOK_FORMATS)