fix(jellyfin): off-media instant registration + native-webhook multi-version

[stevezau]

Closes the two remaining multi-version / off-media edges flagged after #269/#271. Both Jellyfin-specific; live-verified on Jellyfin 10.11.11.

1. Off-media instant trickplay registration (was silently 404'ing)

The app POSTed /MediaPreviewBridge/Trickplay/{id} without saveWithMedia, so the plugin defaulted to true and asked Jellyfin for the media-adjacent tile dir — which an off-media publish never writes — and returned 404. Registration then fell back to the next scheduled metadata refresh instead of appearing immediately. This affected all off-media items (single- and multi-version).

Fix: _trigger_item_refresh now sends saveWithMedia matching the adapter's mode. App-only — no plugin release needed.

Live A/B (alternate version, off-media): POST without the param → 404; with saveWithMedia=false → 204 registered. The real trigger path now logs Registered trickplay via Media Preview Bridge plugin for every version.

2. Native Jellyfin webhook → every version

A native Jellyfin webhook resolving an item id previewed only the primary version of a merged item (alternates live in MediaSources). Added resolve_item_to_remote_paths(item_id) -> [(version_id, path)]:

• base: the single resolve_item_to_remote_path result.
• Jellyfin/Emby: every MediaSource (each tagged with its per-version GUID for off-media); Emby yields one (versions are separate item ids → no fan-out, matches the scan).
• Plex: every media[*].parts[*].file by bare ratingKey — brings the universal /incoming router to parity with /webhook, which already fanned out.

webhook_router resolves to a list and fans out one Job per version. Single-version and all Sonarr/Radarr path webhooks return the byte-identical one-job response; multi-version returns {"status":"queued","version_count":N,"jobs":[...]}. server_id_filter is threaded into every version's Job.

Live: resolve_item_to_remote_paths returns both versions with distinct GUIDs against real Jellyfin.

Tests

saveWithMedia matrix (media-adjacent / off-media / default); per-version resolvers (Plex parts, Jellyfin MediaSources, failure → []); router fan-out (Plex + Jellyfin) with per-version hint assertions; per-server URL pins every version; Emby item-id does not fan out. Full suite green (the only failures are the known flaky xdist worker-crash pollution — all pass in isolation). Architecture Review run; no HIGH, the MED + 2 LOW (test-matrix gaps) closed before commit.

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 82.45614% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.00%. Comparing base (984c7b9) to head (2a88764).

Files with missing lines	Patch %	Lines
media_preview_generator/web/webhook_router.py	81.81%	6 Missing ⚠️
media_preview_generator/servers/base.py	33.33%	2 Missing ⚠️
media_preview_generator/servers/plex.py	85.71%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #272      +/-   ##
==========================================
+ Coverage   83.97%   84.00%   +0.03%     
==========================================
  Files          89       89              
  Lines       19599    19632      +33     
==========================================
+ Hits        16458    16492      +34     
+ Misses       3141     3140       -1     

Files with missing lines	Coverage Δ
media_preview_generator/servers/_embyish.py	84.55% <100.00%> (+0.15%)	⬆️
media_preview_generator/servers/jellyfin.py	83.08% <100.00%> (+0.02%)	⬆️
media_preview_generator/servers/base.py	82.92% <33.33%> (-0.74%)	⬇️
media_preview_generator/servers/plex.py	81.16% <85.71%> (+0.09%)	⬆️
media_preview_generator/web/webhook_router.py	80.61% <81.81%> (+0.93%)	⬆️

... and 3 files with indirect coverage changes

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