book3: finalize ruin backstory revision (ch01 audit + sweep)

- Ch01 audit: verified no stale canon references survived
- Cross-file consistency sweep clean for the four stale
  patterns (root cellar, Wolf note, pixie dragon, symbiote)
- series-arc.md: "pixie dragon" → "true dragon (Mine 1 earth-magic mutation)"
- Memory updated: spec marked implemented

Closes: docs/superpowers/specs/2026-04-19-book3-ruin-backstory-revision-design.md

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

outline/series-arc.md

@@ -61,7 +61,7 @@ Life-force drainings across Drenwick trace back to Kae, a street kid weaponised
 
 **The Arcane Compact becomes a direct pressure; Phelan's ability can no longer stay quiet.**
 
-A pre-Compact ruin (the Athel Repository) on Duchess Pamira's territory near Thorngate. A previous guild operative died clearing the first chamber. Ledger assigns Phelan because the wards require someone who can read pre-Compact architecture — and because the job gets him out of Drenwick while the Compact inquiry into the Book 2 crystal break is pending.
+A pre-Compact ruin (the Athel Repository) on Duchess Pamira's territory near Thorngate — surveyed 20 years ago by a Pathfinder team that included Devod, then deferred when the sealed perimeter gate proved unbreakable. A guild scout deployed to re-assess the site was killed by that same gate ward. Ledger assigns Phelan because the wards require someone who can read pre-Compact architecture, because Devod's name is in the original survey, and because the job gets him out of Drenwick while the Compact grievance on the Book 2 crystal break is pending.
 
 **The core inversion:** Phelan opens a sealed chamber, sees an amplification weapon inside, and realises it must be re-sealed. He cannot repair the original architecture — he has to build a new seal from scratch. A perfect lock. Something his own Flaw Sight cannot crack. The man who finds every flaw must create something without any. Leon becomes the testing framework — he attacks with brute force, Phelan sees the leaks and rebuilds. Their complementary approaches become a design process.
 
@@ -72,7 +72,7 @@ A pre-Compact ruin (the Athel Repository) on Duchess Pamira's territory near Tho
 - **Mere is pregnant.** The anticipation IS the arc. She says "home" about Chandler's Row for the first time without qualification.
 - **Devod meets Duchess Pamira.** Two old soldiers recognising each other on purpose. He calls her "princess" (wrong rank). She says "DEVOD!" (correct response).
 - **Ledger's Pathfinder reveal.** Full. "Cairns." One word. Everything from Book 2 clicks.
-- **Pip** — a pixie dragon bonds with Mere and becomes a living magic detector.
+- **Pip** — a true dragon (Mine 1 earth-magic mutation) bonds with Mere and becomes a living magic detector.
 - **Phelan discovers the flawfinder's gift documented in the archive.** He is not the first. Not alone. First meaningful answer to the question of what he is.
 
 ### Book 4+ *(seeds only)*