fix(map): keep muted popup text AA on Leaflet's white popups

Token text-ink-muted is #8C98AE in dark mode, ~2.9:1 on the always-white
popups (node, incident, path-stop, AIS, 511 camera). Scoped override to
#5B6577 (~6:1). Found in tonight's regression review.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-frontend/app/globals.css

@@ -199,6 +199,13 @@ html:not(.dark) .border-indigo-800 { border-color: #a5b4fc !important; }
   filter: invert(1) hue-rotate(180deg) brightness(0.9) contrast(0.9) saturate(0.6);
 }
 
+/* Leaflet popups stay white in both themes (their body text is a fixed
+ * gray-900), so the theme's muted ink — light grey in dark mode, ~2.9:1 on
+ * white — is pinned to a grey that holds AA on white (~6:1). */
+.leaflet-popup-content .text-ink-muted {
+  color: #5B6577;
+}
+
 /* Pinned 511 camera tiles (MapView DotCameraLayer): strip Leaflet's tooltip
  * padding and let the tile's own theme colours show, so the tile is no bigger
  * than the video it holds. */