Add subdl unpack=1 support and fix anime season matching

[mi3lix9]

Summary

Two related improvements to the subdl provider:

1. Support subdl's new unpack=1 API parameter

Subdl recently introduced an unpack=1 option that returns individual episode subtitle files (unpack_files[]) for season packs / multi-episode ZIPs, each with its own direct download URL.

This PR sends unpack=1 on all TV subtitle searches and, when a pack is detected for the target episode, uses the direct per-episode URL instead of downloading the whole ZIP. This avoids the smart-extract step entirely and is significantly faster for episodes inside large season packs.

Implementation details:

• New is_direct_file flag on SubdlSubtitle to distinguish raw subtitle responses from ZIPs.
• query() adds ('unpack', 1) to all four TV API calls (episode, absolute-episode, season-only, title-only). Movies excluded.
• After pack detection, the item's unpack_files[] is searched for an entry matching video.episode (or video.absolute_episode). On hit, download_link is swapped to the unpack URL, is_pack cleared, season/episode taken from the unpack entry, and file_id made unique with the file_n_id.
• download_subtitle() handles the non-ZIP response by treating r.content as raw subtitle text via the already-imported fix_line_ending. Falls back to the old ZIP path unchanged when unpack_files is empty or no match.

2. Trust the season when an episode is matched via absolute_episode

Some anime uploads on subdl are tagged with season=0 (or arc-based season numbering that differs from Sonarr's). With the existing logic, season wasn't added to matches in that case, and Bazarr's series/episode gate then filtered the subtitle out — even though the absolute episode number uniquely identifies the (season, episode) pair.

The fix adds season to matches whenever the episode was matched by absolute number. Concrete example that motivated this: One Piece S23E01 (absolute episode 1156) — the [Erai-raws] subtitle (matching the user's release group exactly) was tagged season=0, episode=1156 on subdl and was being skipped.

Test plan

• unpack=1 query returns unpack_files[] from the live subdl API
• Provider end-to-end: pack item is detected, unpack entry matched by episode, direct URL stored, ZIP path skipped
• download_subtitle correctly takes the is_direct_file branch and produces valid subtitle content (verified with a real One Piece S02E01 .ass download — 88 KB, proper BOM + [Script Info] header)
• Backward compatibility: items without unpack_files (movies, older subdl entries) fall through to the existing ZIP behavior unchanged
• Season-via-absolute-episode fix: the previously-skipped [Erai-raws] One Piece 1156 subtitle now scores correctly and is selectable in the UI