v3.1.7 - zip file fix, client names, device area groupings etc

[3.1.7]

Fixed

• Client sub-group boxes rendered enormous whenever Show Client
  Names was on - root-caused via direct browser DevTools inspection
  after an initial layout-based fix didn't resolve it. The actual
  cause was a JavaScript string-concatenation bug in 3.1.6:
  individual_devices_group_padding arrives as the string "6"
  (config values commonly do), and the extra bottom padding added for
  Show Client Names was computed as pad + 18 - since pad was a
  string, + concatenated rather than added, producing "618" (as in
  618px) instead of 24. Every group box independently carried this
  same broken padding, which is why it affected every box uniformly
  regardless of its own content. pad is now coerced to a real Number
  at its source, not just at the one call site that happened to do
  arithmetic on it, so the same class of bug can't resurface through
  some other future use of the same variable.
• Invalid <rect> attribute errors on every Clients box render
  ("Invalid value for <rect> attribute width="calc(100% - 2px)"",
  visible in the browser console) - calc() is only valid for SVG
  geometry properties when set through CSS (the style attribute or a
  stylesheet), not as a plain XML attribute value, which is how width
  and height were set on the dashed-border rect drawn behind the
  Clients box and each of its sub-groups. Moved both into the style
  attribute alongside rx/ry, which were already handled correctly
  this way. A real, confirmed bug, but a cosmetic one on its own - the
  SVG's own outer size was already correct via CSS regardless, so this
  didn't contribute to the height issue above.
• Sub-group boxes no longer stretch to match whichever sibling is
  tallest (align-items: flex-start instead of stretch on their
  shared flex container). This turned out not to be the cause of the
  height issue above, but is a real fix in its own right: without it,
  one heavily-populated group wrapping onto multiple rows could still
  impose its height on every sibling regardless of their own content.
• The Internet circle's outline now defaults to the Billing
  Remaining color when no billing entities are configured at all,
  instead of falling back to the Internet circle's general theme
  color. Previously, once billing entities were set, the plain circle
  border went transparent in favor of the SVG progress ring drawn on
  top of it (colored by Billing Remaining/Billing Progress) - but
  without billing configured, the border fell back to whatever generic
  color the Internet circle otherwise uses, which read as unrelated
  to billing styling entirely. This distinguishes "billing configured
  but a sensor value is temporarily unavailable" (still falls back to
  the general circle color, unchanged, so the border doesn't flicker
  colors as a sensor briefly goes unavailable) from "billing was never
  configured for this Internet entity" (now uses Billing Remaining
  color specifically).
• The editor is no longer a separate lazily-loaded file -