Fix desktop layout bugs and show more incident actions directly

On-call, the incident queue and the account page all had latent CSS bugs
that only show up once the browser is wide enough to hit the desktop
breakpoint (900px+):

- On-call: .days reset its own margin to 0, which canceled the page-wide
  auto-centering on just that element, leaving the day list pinned to the
  left edge while every other card on the page centered normally.
- Queue: the list pane stayed capped at 340-420px even with nothing
  selected, leaving the rest of the screen empty. It now fills the width
  until an incident is picked, then goes back to list+detail.
- Account, admin user and admin team: .btn and .back-link are inline-flex,
  and margin:auto only centers a block box, so the Sign-out button and the
  two admin back-links sat left of their sibling cards instead of matching
  their width. Wrapped each in a block div.

The incident detail action bar also folded Assign, Add note, Resolve and
Clear acknowledgement into a "More" sheet sized for a phone's width.
Desktop has the room, so it now shows them as direct buttons and hides
More instead; Copy incident stays out of the bar since the header already
has its own button for it.

Filed as niklas/terdut-server#31, #32, #33, #34, each with a screenshot.

internal/web/static/app.css

@@ -583,6 +583,10 @@ details[open] > summary { margin-bottom: 8px; }
 }
 .actionbar .btn { min-height: 48px; }
 .actionbar .btn-primary { flex: 1; font-size: 16px; }
+/* The extra actions that only phones hide behind "More" — see actionBar() and
+   extraActions() in incident.js. Hidden by default; the desktop block below
+   shows them and hides the now-redundant More button instead. */
+.action-extra { display: none; }
 
 .detail-placeholder {
   display: grid; place-items: center; height: 100%;
@@ -669,7 +673,7 @@ details[open] > summary { margin-bottom: 8px; }
    caught by the unrelated .label > span styling meant for label chips. */
 .week-nav .week-label { font-size: 14px; font-weight: 650; min-width: 11.5em; text-align: center; white-space: nowrap; }
 .week-label small { color: var(--faint); font-weight: 600; font-size: 11px; margin-left: 2px; }
-.days { list-style: none; margin: 0; padding: 0; }
+.days { list-style: none; margin: 0 auto; padding: 0; }
 .day { display: grid; grid-template-columns: 3.2em 4.2em 1fr; align-items: center; gap: 8px; min-height: 50px; padding: 0 14px; }
 .day + .day { border-top: 1px solid var(--border); }
 .day-name { font-weight: 650; }
@@ -773,7 +777,15 @@ kbd {
   .pane-list .chips { flex-wrap: wrap; overflow-x: visible; }
   .pane-list .chip-sep { display: none; }
   .chips-fade { display: none; }
-  .view-queue:not(.has-detail) .pane-detail { display: block; }
+  /* With nothing selected there is no detail to show next to, so the list
+     takes the whole row instead of leaving the second column as dead space
+     around the placeholder text. Selecting an incident (.has-detail) drops
+     back to the base minmax(340,420) 1fr rule above. */
+  .view-queue:not(.has-detail) { grid-template-columns: 1fr; }
+  .view-queue:not(.has-detail) .pane-list { border-right: 0; }
+  /* Full width reads better capped than edge-to-edge on a very wide monitor,
+     matching .detail's own cap below. */
+  .view-queue:not(.has-detail) .list { max-width: 900px; margin: 0 auto; }
 
   /* On desktop the list stays visible next to the detail. */
   .app.detail-open .nav { display: flex; }
@@ -787,8 +799,12 @@ kbd {
   .actionbar {
     position: sticky; bottom: 0;
     padding: 12px 32px;
+    flex-wrap: wrap;
   }
   .actionbar .btn-primary { flex: 0 1 240px; }
+  /* Room enough to show every action, so More is fully redundant here. */
+  .action-extra { display: inline-flex; }
+  .more-btn { display: none; }
 
   .sheet {
     width: min(440px, calc(100% - 32px));