fix(video): fix two remaining bugs in Specials numbering and long-season episodes

1. A season spanning more than one folder (a per-book Bonus folder nested
   inside every numbered season) got the same synthetic episode numbers
   handed out again in each folder independently — three unrelated
   Specials all showing up as "S0E01". _synthetic_episode_number now ranks
   across the whole show for the target season, not just one file's own
   folder.

2. guessit reads a bare 3-digit leading episode number as a concatenated
   season+episode guess rather than a plain episode number — "100" parses
   as season=1, episode=0, not episode=100, with nothing in its output
   distinguishing that from a real 2-digit episode. A season-like ancestor
   already overrides guessit's season (previous commit); this applies the
   same fix to episode via a direct regex on the leading number, capped at
   3 digits so a leading year (4 digits) is never misread the same way.

Both confirmed against the real library this whole fix was found on:
per-book Bonus features across two books no longer collide, and a real
100th-episode file now resolves to episode 100 instead of 0.

1 files changed, 25 insertions, 0 deletions

diff --git a/packages/meshbay-node/tests/test_title_parse.py b/packages/meshbay-node/tests/test_title_parse.py
index 1881613..cf51646 100644
--- a/packages/meshbay-node/tests/test_title_parse.py
+++ b/packages/meshbay-node/tests/test_title_parse.py
@@ -6,6 +6,7 @@ is a manual acceptance step (§11), not something this repo's corpus holds.
 
 from meshbay_node.indexer.title_parse import (
     ParsedName,
+    leading_episode_number,
     naive_title,
     parse_episode_filename,
     parse_movie_filename,
@@ -128,6 +129,30 @@ def test_non_season_folder_name_returns_none():
     assert season_from_folder_name("Some Show Name") is None
 
 
+# ── §3.4c: a bare leading episode number, guessit's 3-digit blind spot ───────
+
+def test_leading_episode_number_reads_the_whole_number():
+    assert leading_episode_number("001    Episode's Own Title.mkv") == 1
+    assert leading_episode_number("099    Episode's Own Title.mkv") == 99
+
+
+def test_leading_episode_number_not_split_by_guessit_at_three_digits():
+    # The real bug this guards: guessit itself reads a bare "100" as season=1,
+    # episode=0 (a concatenated SxxE guess), not episode=100 — silently, with
+    # nothing in its output telling apart a real 2-digit episode from this.
+    assert leading_episode_number("100    Episode's Own Title.mkv") == 100
+
+
+def test_leading_episode_number_ignores_a_leading_year():
+    # Four digits, not the 1-3 an episode-number prefix can be — this is a
+    # normal movie filename shape, not an episode number.
+    assert leading_episode_number("2010 - Some Movie.mkv") is None
+
+
+def test_leading_episode_number_none_without_a_leading_number():
+    assert leading_episode_number("Some Show.S01E01.mkv") is None
+
+
 def test_parsed_name_is_a_plain_dataclass():
     # sanity: constructible with just the one required field, per the
     # "None => caller must supply from elsewhere" contract.