Check unmatched media at season and episode level

Checking only shows and movies was hiding the larger problem. Battlestar
Galactica has a real plex:// GUID, a poster, and passes a show-level audit,
while all 74 of its episodes and all 5 of its seasons carry local:// GUIDs and
display as "Episode 1", "Episode 2" with no titles or artwork.

Surveying every level found 97 unmatched episodes of 11531 and 7 unmatched
seasons of 954, across four shows — none of it visible before.

Also adds known-issues.conf, an accepted-findings list. The unmatched movie in
the Movies library is the first entry: the 2003 BSG miniseries is catalogued as
television, so the movie agent has no record to match it against and the item
cannot be fixed in place. Listed entries are still printed, as [info] rather
than [warn], so they stop counting as unresolved faults without ever being
silently suppressed.

The episode list is a ~30MB response, so it is written to a temp file before
parsing rather than piped into jq.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

plex/docs/unmatched-media.md

@@ -0,0 +1,75 @@
+# Unmatched media (surveyed 2026-08-15)
+
+An unmatched item carries a `local://` GUID instead of a real agent GUID
+(`plex://movie/...`, `plex://episode/...`). Plex will never give it a title, summary, or
+artwork, and no amount of poster repair will help — there is no metadata record behind it.
+
+## Why the top level is not enough
+
+**A matched parent can be full of unmatched children.** This is the finding that matters:
+
+- `Battlestar Galactica` the *show* has a real GUID, a poster, and looks completely
+  healthy in a show-level audit.
+- All **74 of its episodes** and all **5 of its seasons** carry `local://` GUIDs. They
+  display as "Episode 1", "Episode 2"… with no titles and no artwork.
+
+An audit scoped to shows and movies reports this library as clean. `plex-health` checks
+show, season, and episode level for exactly this reason.
+
+## Current state
+
+| Level | Unmatched | Total |
+| --- | --- | --- |
+| Movies | 1 | 1059 |
+| Movies 4k | 0 | 79 |
+| Shows | 0 | 283 |
+| Seasons | 7 | 954 |
+| Episodes | 97 | 11531 |
+
+Episodes by show:
+
+| Show | Unmatched | Of total | Note |
+| --- | --- | --- | --- |
+| Battlestar Galactica | 74 | 74 | every episode |
+| Louis Theroux | 19 | 19 | every episode |
+| Hellsing Ultimate | 3 | 13 | partial |
+| Ancient Aliens | 1 | 205 | single episode |
+
+## Battlestar Galactica: three copies, none of them right
+
+Worth understanding as a whole before changing anything:
+
+1. **`Movies` → `Battlestar Galactica the Mini Series`** (`19798`, `local://19798`)
+   `/data/Movies/Battlestar Galactica - The Mini-Series (2003)/…Bluray-1080p.mkv`
+   94 min, 1080p, 11.06 GB. **Unmatchable in a Movies library** — Plex's movie agent has
+   no entry for the 2003 miniseries, which is catalogued as television. All 20 candidates
+   it offers are documentaries or the Razor/Plan films. Accepted in
+   [../known-issues.conf](../known-issues.conf); the structural fix is to move the file
+   into the TV library, which needs filesystem access to odin.
+
+2. **`TV Shows` → `Battlestar Galactica (2003)` → `Season 2003`** (2 episodes)
+   `/data/TV/Battlestar Galactica (Miniseries)/Season 2003/…S2003E01…`
+   576p, ~2 GB per part, 94 + 89 min. The same miniseries, at lower quality but complete.
+   The `S2003E01` filename is what created the bogus "Season 2003" — the agent expects
+   specials as season 0 (`S00E01`).
+
+3. **`TV Shows` → `Battlestar Galactica (2003)` → Seasons 1–4** (74 episodes)
+   Filenames are correct and carry real episode titles
+   (`… - S01E01 - 33.mkv`, `… - S01E02 - Water.mkv`), yet every episode is `local://`.
+   The show matched; its episodes never did.
+
+Note that (1) and (2) are **not** interchangeable copies: the Movies file is higher
+resolution but 94 minutes against the TV pair's 183, so it is likely part one only rather
+than a complete alternative.
+
+## Not yet attempted
+
+Re-matching the 97 episodes. A forced metadata refresh
+(`PUT /library/metadata/<key>/refresh?force=1`) is the obvious lever, and for a show whose
+filenames are already correct it would probably match them.
+
+**It carries a specific risk here:** a forced refresh rebuilds the item's metadata,
+which is precisely the operation implicated in the poster failure documented in
+[tv-poster-incident.md](tv-poster-incident.md). Running it across the library could undo
+the poster repair. If it is attempted, do it on **one** show first, then re-run
+`bin/poster-audit` to confirm the posters survived before going wider.