fix(screenshots): level the elevation cameras for straight verticals

archviz rule: an elevation must not lean. hero-facade-front looked up ~4 deg from
4.2 m at a 7.6 m target (columns converged); demo-spawn-view and demo-street-level
were pitched too. All three now sit at the target's height, so pitch and roll are
zero by construction and the verticals stay parallel.

Screenshots re-rendered. A pixel-based verticality check is useless here (banners
and windows break naive edge matching), so the guarantee is geometric and is
recorded that way in the README and MEMORY.

MEMORY.md

@@ -495,3 +495,15 @@ Scope: facts and traps that cost time to establish. Planned work lives in [TODO.
   `v0.1.2` cut after the merge.
 - Assumptions recorded rather than hidden: dentil spacing, base and abacus
   dimensions are not resolvable in our reference photography.
+
+## 2026-11-09 — elevation cameras levelled (straight verticals)
+
+- archviz MUST: an elevation must not lean. `hero-facade-front` looked up ~4° from
+  4.2 m at a 7.6 m target; `demo-spawn-view` and `demo-street-level` were pitched
+  too. All three now put the camera at the target's height, so
+  `FindLookAtRotation` yields pitch 0 and roll 0 and verticals are parallel by
+  construction.
+- Do not try to *measure* verticality from the rendered PNG with a naive edge
+  scan: banners, windows and the parapet produce different edge sets at different
+  heights and the pairwise match is meaningless (it reported a 418 px "drift").
+  Verify it geometrically in the camera list instead.