Fix intermittent episode artwork not updating on filters page

[lromero16]

Description

Fixes #PCDROID-79

Root cause: PodcastEpisode.thumbnailStatus has three constants — THUMBNAIL_STATUS_UNKNOWN, THUMBNAIL_STATUS_EMBEDDED_AVAILABLE, and THUMBNAIL_STATUS_EMBEDDED_NOT_AVAILABLE — but PlaybackManager.onMetadataAvailable() never set it. When embedded artwork is extracted from a downloaded audio file during playback and saved to the artworkCacheFile on disk, the episode's DB record was never updated. Because Room didn't re-emit, DiffUtil detected no changes, and the filters page ViewHolder was never rebound to show the newly extracted artwork.

Fix: After saving chapters in onMetadataAvailable(), fetch the episode and set thumbnailStatus to the appropriate value (only once, when still THUMBNAIL_STATUS_UNKNOWN). This DB write triggers Room → DiffUtil → onBindViewHolder → bindArtwork() → Coil loads from the local cache file.

Testing Instructions

1. Find a podcast episode that has embedded artwork (common in many podcasts)
2. Open the filters page — note the episode shows podcast-level CDN artwork
3. Play the episode to completion or for a few seconds (allowing the player to read metadata)
4. Return to the filters page — the episode should now show its embedded artwork without needing to scroll

Screenshots or Screencast

Checklist

• If this is a user-facing change, I have added an entry in CHANGELOG.md
• Ensure the linter passes (./gradlew spotlessApply to automatically apply formatting/linting)
• I have considered whether it makes sense to add tests for my changes
• All strings that need to be localized are in modules/services/localization/src/main/res/values/strings.xml
• Any jetpack compose components I added or changed are covered by compose previews
• I have updated (or requested that someone edit) the spreadsheet to reflect any new or changed analytics.

I have tested any UI changes...

• with different themes
• with a landscape orientation
• with the device set to have a large display and font size
• for accessibility with TalkBack

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[dangermattic]

	1 Error
🚫	PR requires a [Type] label and either a [Area] or [Project] label.

	1 Warning
⚠️	PR is not assigned to a milestone.

Generated by 🚫 Danger

[geekygecko]

Can you please follow the checklist in the PR description template, include screenshots or video, and sign the CLA.

[geekygecko]

@copilot review this

[Copilot]

@copilot review this

Code review findings for the PR:

Bug found: The original onMetadataAvailable() change incorrectly sets THUMBNAIL_STATUS_EMBEDDED_NOT_AVAILABLE when useEpisodeArtwork=false. In that case, EpisodeFileMetadata.read() skips artwork extraction entirely — embeddedArtworkPath is always null — but the code was treating that as "no embedded artwork". If the user later enables the setting, the episode's thumbnailStatus is no longer UNKNOWN, so it would never be re-evaluated and the artwork would never appear.

Fix prepared (commit e76f3a8, pending push):

• Extracted into internal fun resolveThumbnailStatus(embeddedArtworkPath, useEpisodeArtwork): Int? — returns null when useEpisodeArtwork=false (extraction not attempted), so the status stays UNKNOWN for future evaluation; returns THUMBNAIL_STATUS_EMBEDDED_AVAILABLE when artwork was extracted; returns THUMBNAIL_STATUS_EMBEDDED_NOT_AVAILABLE only when extraction was attempted but no artwork was found.
• Added ResolveThumbnailStatusTest covering all three cases.

Note: The push is currently blocked by the danger/pr-check required status check, which is failing due to missing PR [Type] and [Area]/[Project] labels (see Danger bot comment). Once labels are added, the check will pass and the fix commit can be pushed.