focus: keys go where the screen says they go

A password prompt now hands the focus back to whatever had it before it
opened, or to the editor or the list when that is gone. Until now the
focus was left on nothing once the field went away, so after an :unlock
typed in the editor the status line still said NORMAL while j walked the
list and dd asked to delete the document. A key that lands outside the
editor while it is open is handed back to it for the same reason.

A document or folder asked for from the board — T, :12, :e, a search —
is now shown instead of being opened in a tree hidden behind the board,
and closing such a document goes back to the board. A space switch that
reopens a remembered document still keeps the board on screen.

Unlocking the vault says so while the key is stretched.

web/src/App.svelte

@@ -443,6 +443,15 @@
 
     if (cmdline !== null || isTypingTarget(event.target)) return
 
+    // While writing, the status line says the editor is listening. A key that
+    // lands anywhere else — the focus left behind by a prompt, a click on the
+    // header — hands the focus back to it instead of walking the list unseen.
+    if (workspace.editing && workspace.pane === 'document' && !event.ctrlKey && !event.metaKey && !event.altKey) {
+      event.preventDefault()
+      hooks.focusEditor()
+      return
+    }
+
     // Ctrl-P: find anything, in any space — the one search that is not
     // confined to where you are.
     if (event.ctrlKey && !event.metaKey && !event.altKey && event.key === 'p') {