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/11-command-nexus.md

@@ -24,6 +24,8 @@ The single source of truth for **every command and action the app can perform**
 | File | New Board… (opens the template chooser) | ⌥⌘N | Everywhere |
 | File | Open… | ⌘O | Everywhere; standard open panel (boards = `.kanban` packages and extension-less board folders — 01) |
 | File | Open Recent ▸ (with Clear Menu) | — | Everywhere; reads the board registry (02) |
+| File | Import Board… (open panel → format detected, never user-picked — Obsidian Kanban frontmatter marker, `.csv`, lenient Markdown outline as the unfailable fallback → save panel places the fresh `.kanban`, which opens the ordinary way) | — (no default) | Everywhere, no board needed in front; 15-import-export.md |
+| File | Export ▸ Obsidian Kanban Markdown… / Markdown Outline… / CSV… (three named rows, no format popup — menu titles are API here, and a title whose meaning lives in a popup would be one title standing for three commands; each row a save panel pointed at the right extension; omissions post a loss row, silent when lossless) | — (no defaults) | Board window; 15-import-export.md |
 | File | Board Info (toggles the board popover — opens it closed, closes it open) | ⌘I | Board window |
 | File | Duplicate (the board — a Finder-style "copy" sibling, 03 ▸ Welcome; never the selection) | ⇧⌘S | Board window |
 | File | Save as Template | — (no default) | Board window; 09-templates.md |