Map: pin 511NY camera feeds as tiles on the map (#183)

Clicking a camera's snapshot pins a 192x108 tile anchored at the camera --
the live HLS stream when the camera has one (hls.js; Safari native), else the
snapshot refreshed every 60s, falling back to the snapshot if the stream dies.
Up to 6 pins, oldest dropped. Players exist only while the DOT Cameras overlay
is on, so hiding it stops every stream.

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

drb-frontend/app/globals.css

@@ -177,6 +177,18 @@ html:not(.dark) .border-indigo-800 { border-color: #a5b4fc !important; }
   z-index: 0;
 }
 
+/* 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. */
+.leaflet-tooltip.drb-cam-pin {
+  padding: 0;
+  border-radius: 6px;
+  background: var(--surface);
+  border: 1px solid var(--line-strong);
+  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.45);
+  white-space: normal;
+}
+
 /* ── Form inputs ─────────────────────────────────────────────────────────── */
 html:not(.dark) input:not([type="submit"]):not([type="button"]):not([type="reset"]),
 html:not(.dark) select,