feat(cv): harden multi-page builder

Wrap pathological content, paginate oversized entries, measure A4 and Letter previews correctly, unify section ordering, and gate stored-output actions on saved state.

docs/architecture/cv-builder.md

@@ -76,8 +76,15 @@ variant, never on the profile. Each entry exposes hide, title/subtitle override,
 editing (`RichTextField` — a markdown toolbar over a textarea; storage stays plain text, the server
 renderer converts the `**bold** *italic* __underline__ [text](url)` whitelist to safe HTML).
 
-**Preview** has zoom presets (±, slider, Fit), a measured page count with prev/next page navigation
-and dashed page-break indicators, and an "updating…" chip. **Customize** badges ATS-friendly themes.
+**Preview** has zoom presets (±, slider, measured Fit), physical A4/Letter dimensions, a ceiling-based
+page count with prev/next navigation and page-break indicators, and an "updating…" chip. Three-page
+and longer documents receive content-focus guidance rather than automatic font shrinking. Preview
+requests and autosaves are ordered so stale responses cannot replace newer edits; PDF/public actions
+save the current variant before consuming the stored render. **Customize** badges ATS-friendly themes.
+
+Profile-backed and custom sections share one section order. Custom-section content remains stored in
+`CustomSections`, while `Sections` holds its `custom:<key>` position and visibility. Legacy variants
+without those order rows still append custom sections and acquire the shared order on their next edit.
 
 ## AI