The corpus index and the Nexus learn the interchange rows — and the import/export doc stops quoting words the owner never said

DESIGN/15's open-questions bullet claimed the owner's literal word was
"proceed as per your recommendation for v1"; no such message exists. The
rulings were inferred by the implementing session from the card's move to
Approved, and the doc now says exactly that. README gains the 15 row,
11-command-nexus gains File ▸ Import Board… and the three Export rows.

Claude-Session: https://claude.ai/code/session_014PtZdPwqZuqEDLc6wZMtEy

DESIGN/README.md

@@ -27,6 +27,7 @@ Each document covers one aspect of the design. Within each:
 | [12-editions.md](12-editions.md) | The tiers — **mooted 2026-08-08**: one version, everything free, tier machinery excised; Pro returns with the iPhone/sync era as a fresh pass (the doc is record: entitlement mechanics, distribution, the git rows) |
 | [13-native-undo.md](13-native-undo.md) | macOS-native undo/redo — the history substrate (sole since 2026-08-08); owns Undo routing |
 | [14-git-operations.md](14-git-operations.md) | Extracted pathfinder git-operations conclusions — **retired 2026-08-08** (superseded record) |
+| [15-import-export.md](15-import-export.md) | Import/export: interchange formats — Obsidian Kanban, Markdown outline, CSV — and the Obsidian vault interop posture |
 
 ## Deferred design iterations