press v2.2.1

Mobile and boundary repairs, no design change to any book. The documentation
site's masthead no longer collapses and its wide tables read on a phone; a
book's own web tables stack on a narrow screen while rendering byte-identically
at reading width; and a registration lookup bounds its response as it reads it.
Compatible within v2.

Fixed

• A registration lookup bounds the response body as it reads it (#209).
  The size cap was applied to the body the transport had already read, so a
  server that omitted or lied about Content-Length decided how much memory
  a lookup spent before the cap could refuse it. The bound now travels with
  the request: adapters.http.urlopen_transport takes an optional
  max_bytes and reads one byte past it, so an overrun is visible and fails
  closed rather than being truncated in silence. It is opt-in and unbounded
  by default -- a cover image and a provider payload legitimately read
  whatever the server sends, and a blanket cap would silently truncate them.

• Wide tables are readable on a phone, on every HTML surface the press
  publishes. A three- or four-column table used to run its far columns off
  the edge: on the docs site it scrolled sideways inside its own box, and in a
  book it fell back to browser defaults, which styled it not at all. Narrow
  screens now stack each row into a card, and every cell wears its column's
  header -- carried onto the cell as data-label by
  webmeta.label_table_cells when the page is built, because CSS cannot reach
  a cell's header on its own. One implementation serves the docs site, the
  book's reader pages, the landing page, and the single-file HTML edition.
  On the book surfaces the change is scoped to the narrow breakpoint and
  nothing else: at reading width a book's tables render exactly as they always
  have (proven pixel-identical), because within a major the press may correct
  broken output but must not restyle a valid book. Giving tables a house
  treatment at every width is a design change and waits for the next major.
  Tables with no header row -- the reference records, a book's downloads
  list -- already read in two columns and are deliberately left untouched.

• The masthead lockup no longer collapses on the documentation site. The
  desktop sidebar is a column flex container capped at the viewport height, and
  the lockup's overflow:hidden zeroed its automatic minimum size, so under
  shrink pressure the box collapsed to nothing and sheared the logo to a sliver
  at every desktop width. The browser layout check now measures the clipping
  box against the image -- the image reported its full height throughout -- and
  refuses a stacked table that still scrolls sideways or clips a cell.