fix(plex-scanner): add TVDb to TMDB fallback in plex scanner

[fallenbagel]

Description

When Plex doesn't include a tmdb:// entry in a title's GUID array and only provides a tvdb:// ID, the scanner fails with "Unable to find TMDB ID" even though the title exists on TMDB with a valid TVDb external ID mapping. The existing code only had a fallback path from IMDb to TMDB but was missing the equivalent TVDb to TMDB lookup. This adds that fallback in getMediaIds for the Plex agent, matching the approach already used by the Jellyfin scanner.

• Fixes Unable to find TMDB ID for title that does exist on TMDB #2524.

How Has This Been Tested?

Screenshots / Logs (if applicable)

Checklist:

• I have read and followed the contribution guidelines.
• Disclosed any use of AI (see our policy)
• I have updated the documentation accordingly.
• All new and existing tests passed.
• Successful build pnpm build
• Translation keys pnpm i18n:extract
• Database migration (if required)

Summary by CodeRabbit

• Bug Fixes
  • Improved media data retrieval to better handle cases where certain identifiers are unavailable, ensuring more complete information is available for media processing.

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a fallback mechanism to the Plex scanner that retrieves the TMDB ID for media items by using their TVDB ID when a direct TMDB ID lookup is unavailable, enabling downstream processing for media without cached TMDB identifiers.

Changes

Cohort / File(s)	Summary
Plex Scanner Fallback Lookup server/lib/scanners/plex/index.ts	Adds fallback logic to fetch TMDB show data using TVDB ID when TMDB ID is missing, populating the mediaIds.tmdbId for continued processing.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 A show lost in the TMDB night,
Now finds its way through TVDB light,
With IDs swapped and fallback bright,
Reality Check is in our sight! ✨

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Linked Issues check	✅ Passed	The PR directly addresses issue #2524 by implementing a TVDb→TMDB fallback lookup that allows titles with only TVDb GUIDs to be properly resolved, matching the stated objective of finding TMDB IDs from TVDb external IDs.
Out of Scope Changes check	✅ Passed	The change is narrowly scoped to adding a TVDb→TMDB fallback in the Plex scanner's getMediaIds function, directly addressing the linked issue with no extraneous modifications.
Title check	✅ Passed	The title clearly and specifically describes the main change: adding a TVDb to TMDB fallback mechanism in the Plex scanner, which matches the core objective of resolving TMDB IDs when only TVDb GUIDs are available.

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[Copilot]

Pull request overview

This pull request fixes an issue where the Plex scanner fails to process TV shows that only have a TVDb ID in their GUID array without a corresponding TMDB ID. The fix adds a TVDb to TMDB fallback lookup, mirroring the existing IMDb to TMDB fallback pattern already present in the code. This ensures that shows with TVDb external IDs can be properly synced even when Plex doesn't include a direct TMDB identifier.

Changes:

• Added TVDb to TMDB ID fallback in the Plex scanner's getMediaIds method
• Fallback only triggers when TVDb ID exists but TMDB ID is missing
• Matches the pattern used by Jellyfin scanner for similar scenarios

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[0xSysR3ll]

LGTM ! Nice one.