keys: passwords, titles and names without the pointer

A keystore or encrypted key asks for its password as soon as it is
opened, asks again after a wrong one, and Enter on the file pane asks
once more after Escape — the button was the only way in before. Enter on
a sealed file opens the vault the same way.

`:name` on its own, while writing, moves up into the title, and Enter,
Escape, Down or Tab there goes back into the text; the title could not be
reached from the editor at all. `R` starts the command line from the
current name — of the row, the open document, the card or the list —
instead of an empty one.

`s` on a shared document and `y` both ask y/N before they cut readers
off: y is what a vim hand presses to yank, and it retired the live link
without a word.

web/src/lib/Help.svelte

@@ -12,12 +12,12 @@
     ['j / k · ↓ ↑', 'move down / up the list — scroll the document when it has focus'],
     ['gg / G', 'first / last row, or top / bottom of the document'],
     ['Ctrl-D / Ctrl-U', 'half a page down / up the open document'],
-    ['Enter · l', 'open a document, or enter a folder'],
+    ['Enter · l', 'open a document, or enter a folder — on an open keystore or sealed file, Enter asks for its password'],
     ['h', 'from the document to the list, from the list up a level'],
     ['o', 'new document here, straight into insert mode'],
     ['O', 'new folder here'],
     ['i · a', 'edit the open document'],
-    ['R', 'rename what is under the cursor — document, folder or card'],
+    ['R', 'rename what is under the cursor — document, folder or card — starting from its name'],
     ['m / p', 'pick nodes up, then drop them all into the folder you walk to'],
     ['M', 'pick up the whole folder — again puts it all back'],
     ['Ctrl / Shift-click', 'pick a row up · every row up to it — drag them onto a folder'],
@@ -29,8 +29,8 @@
     ['Esc · q', 'close the document'],
     ['/', 'full-text search, inside the current space'],
     ['n', 'clear the search'],
-    ['s', 'toggle sharing for the document'],
-    ['y', 'mint a new share link and copy it'],
+    ['s', 'toggle sharing for the document — asks before taking it back'],
+    ['y', 'mint a new share link and copy it — asks, the old one stops working'],
     ['x · dd', 'delete what has focus — the row in the list, the document in its pane (asks y/N)'],
     [':', 'command line'],
     ['Ctrl-S', 'save, from anywhere'],