phone app: installable, opens offline, takes the share sheet onto the scratchpad, back lets go of one thing

A manifest with a 192, a 512 and a maskable icon, and a hand-written service
worker built beside the app by a small vite plugin: it keeps index.html, the
logo, the entry with its imports and the latin fonts, keeps each hashed asset
once fetched, asks the server for pages first and answers from the cache when
it is down, and never touches /api. The CSP names worker-src and manifest-src.

The share target posts to /share, which the worker catches: the text waits in
a cache and becomes a scratchpad note once someone is logged in, with the
drawer down on it. On a touch screen one guard entry in the history makes back
let go of one thing at a time — a prompt, the line, a sheet, the drawer, the
editor, a tile, then a folder up — and leave only at a space's root. The bar
and the band grow by the safe-area insets. The login no longer says the server
is unreachable once it answers again with the session gone.

docs/wiki/Getting-Started.md

@@ -80,6 +80,9 @@ The rail of buttons on the right does the same as the keys, for a mouse.
 On a phone the same things are buttons: the dock at the bottom has a new
 document, a new folder, the board, today's entry, an upload and a search, and
 the `⋯` on a row (or a long press on it) has what can be done to that row.
+Over HTTPS the browser offers to install it as an app, which then sits in the
+share sheet and puts what is shared on the scratchpad; see
+[On a phone](Guide.md#on-a-phone).
 
 ![The workspace on a phone](../images/mobile-tree.png)