feat(skills): world-building carries the cosmology backdrop

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HuHRPE7VfppUJEaoGBEUqZ

.claude/skills/world-building/references/tone.md

@@ -86,6 +86,22 @@ If you write companion content, hold these exactly — they carry the register:
 - The pair dislike each other mildly and permanently, and neither will leave the
   other. Cadwyn generates, Brannoc annotates. Don't add a third to the loop.
 
+## The cosmic backdrop (the Warden and the Seven)
+
+The world sits inside a hidden war — a distant good god and seven demon kings
+(see `references/cosmology.md`). It colors tone but must never break the world's
+indifference:
+
+- The cosmology is the **hidden engine**, not the surface text. Day-to-day the
+  world is still taxes, mud, and bad men; the war is what's *underneath* them.
+- Demons work **through people** — influence, rarely possession. Write the
+  wreckage and the person going wrong, not a monster in the square. The narrator
+  never confirms the god, never preaches, never goes epic.
+- Which side has hold of someone reads through **Luck's flavor, never a number**
+  (a blessing is a run of fortune; a curse is the trap door opening under you).
+- The good/evil is real but **argued-over** — most folk dispute whether any of it
+  is true. Certainty is the enemy of this tone as much as of §7's Luck.
+
 ## Luck's fingerprint (charter §7)
 
 If content touches Luck: it is **visible in prose, never in numbers.** Never state