Show a basic timeline while the world time is away from live

A bar above the command dock, like a video player's: play and pause on
the left, the world time's date and time in UTC beside it, and Live to
return. It stays hidden while live, so Core looks as before until weather
history is scrubbed or replayed, a host moves the clock, or a link made
away from live is opened. Adds the pause and play_arrow glyphs and the
strings in every catalog.

src/ui/styles/world-timeline.css

@@ -0,0 +1,62 @@
+/* ── World timeline ─────────────────────────── */
+/* Shown while the world time is away from live, centred above the dock. */
+#world-timeline {
+  position: fixed;
+  bottom: calc(2vh + 7rem);
+  left: 50%;
+  z-index: 146;
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  max-width: calc(100vw - 32px);
+  box-sizing: border-box;
+  padding: 4px 6px;
+  border: 1px solid var(--glass-border);
+  border-radius: 10px;
+  background: var(--glass-bg);
+  backdrop-filter: blur(24px) saturate(1.4);
+  -webkit-backdrop-filter: blur(24px) saturate(1.4);
+  box-shadow: 0 8px 28px rgba(0, 0, 0, 0.5);
+  transform: translateX(-50%);
+}
+
+body.ui-clean-view #world-timeline,
+body.recording-mode #world-timeline {
+  bottom: 2vh;
+}
+
+#world-timeline .world-timeline-play,
+#world-timeline .world-timeline-live {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  min-width: 32px;
+  height: 32px;
+  padding: 0 8px;
+  border: 1px solid rgba(123, 189, 211, 0.28);
+  border-radius: 8px;
+  background: rgba(0, 212, 255, 0.08);
+  color: var(--text-primary);
+  font: inherit;
+  cursor: pointer;
+}
+
+#world-timeline .world-timeline-play:hover,
+#world-timeline .world-timeline-live:hover {
+  background: rgba(0, 212, 255, 0.18);
+}
+
+#world-timeline .world-timeline-live {
+  font-size: 11px;
+  letter-spacing: 0.08em;
+  text-transform: uppercase;
+}
+
+#world-timeline .world-timeline-time {
+  overflow: hidden;
+  font-family: var(--font-mono);
+  font-size: 13px;
+  font-variant-numeric: tabular-nums;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}