Adds a season-agnostic fallback to subtitle-episode matching so dropped
subtitle files no longer need a full SxxEyy code to be attached to the
right video. Recognises bare numbers (06, 6, 16), explicit markers
without a season (E06, EP06, Episode 06), and numbers cleanly delimited
by separators, including the common anime release style 'Show - 06 -
Title'. Guards against false positives from resolutions (1080p), years,
and decimal-looking audio tags (DD5.1) by requiring clean separator
boundaries and capping bare numbers at a few digits.
Full season+episode codes still take priority and match exactly as
before; the new bare-number matching only kicks in when one side of the
match lacks season info.
Note: dotnet is not reachable in this environment, so the required
Release build validation could not be run before this commit.