lore(crimson-cult): tie Sztandar shards to Xillith's halberd; reorganize items/

Xillith Isherwood recently finished reassembling the scattered shards of
the Sztandar Szkarłatnego Kultu (the First Patriarch's original staff)
into his halberd, the "Broń Szkarłatnego Patriarchy" - explaining why
Bezimienny's soul, previously fragmented across the shards, is now mostly
reunified. Threaded through the Sztandar item, Bezimienny, and Xillith
Isherwood pages.

Also folds in a prior file move: items/*.md split into items/artifacts/,
items/armor/, items/weapons/, items/gear/ subfolders, with Przedmioty.md
and the two referencing rulebook hubs updated to match, plus a .gitignore
entry for _books/.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019xsdbKAT27PoAX9SWH3MFK

rules/02. Klątwa Otchłani.md

@@ -68,7 +68,7 @@ ___
 ## Rozdział VI - Artefakty
 
 - [Miotacz Energii](../disciplines/Rzemiosło%20Artefaktów.md#Miotacz%20Energii)
-- [Ulepszenie: Miotacz Entropii](../items/Miotacz%20Entropii.md)
+- [Ulepszenie: Miotacz Entropii](../items/artifacts/Miotacz%20Entropii.md)
 
 ___
 ## Aneks A - Kara Mistrza Losu