Validate the design against the live servers, and correct it

Ran the probe and a new reclaim preview against Loki and Tautulli from a LAN
host. The measured library is 65.7 TB across 24 libraries with 60 users and
87,640 logged plays. Five things in the design were wrong or missing.

- Tautulli's get_library_media_info returns file_size 0 for every show
  section regardless of section_type, so it cannot cross-check TV sizes.
  Plex is the only size authority for TV, which is 49 of the 66 TB.
- solitude: divisor of 3 confirmed correct (61.7% of watched items have
  exactly one viewer), but weight raised 0.04 -> 0.10 since on a 60-user
  server "only one person watched this" is real signal.
- rejection: abandonment is 4.9% of plays, not the 30% hoped for. Weight
  cut 0.12 -> 0.06. Kept because it is decisive when it fires.
- Cross-library duplicates promoted from "later candidate" to v1: with 16
  movie sections, Movies and 4K Movies routinely hold the same film.
- Protected libraries added. Family Videos is 38 GB of irreplaceable home
  video that is 86% "never played" and scores as a perfect delete target.

Also splits the reclaim pool into confident (6.5 TB, added while Tautulli
was watching and never played) and uncertain (20.9 TB, predates coverage).
80% of the library predates Tautulli, so pre_history is the majority state,
not an edge case.

Adds tools/reclaim_preview.py, which produced these numbers.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GVbG48GAXfCZatcmX123Ra

.env.example

@@ -40,5 +40,9 @@ SCORE_STALE_HORIZON_DAYS=730
 SCORE_AGE_HORIZON_DAYS=1095
 SCORE_POPULAR_AT=3
 SCORE_REJECTED_AT=2
+SCORE_SOLITUDE_AT=3
 SCORE_GRACE_DAYS=30
+
+# Libraries that must never be scored as deletion candidates (comma-separated).
+PROTECTED_LIBRARIES=Family Videos
 SCORE_RECENT_DAYS=90