fix: clamp max-speed label at edges + move trip location next to time

- placeMaxTick() clamps the label so it stays within the scrubber instead of
  overlapping the time/speed readouts when max speed is near an edge
- give the scrubber row more bottom margin (mb-3) so the tick label clears the
  readout row below
- move the trip location readout directly under the timestamp (left side),
  removing the separate bottom line

static/js/history.js

@@ -168,8 +168,14 @@
         }
         var ratio = st.maxIndex / (st.points.length - 1);
         var thumb = 16; // approximate range thumb width
-        var usable = Math.max(1, scrubber.clientWidth - thumb);
-        tick.style.left = (thumb / 2 + ratio * usable) + "px";
+        var w = scrubber.clientWidth;
+        var usable = Math.max(1, w - thumb);
+        var x = thumb / 2 + ratio * usable;
+        // Keep the centered label inside the scrubber so it doesn't overlap the
+        // time (left) or speed (right) readouts when max speed is at an edge.
+        var halfLabel = 24;
+        x = Math.max(halfLabel, Math.min(w - halfLabel, x));
+        tick.style.left = x + "px";
         tick.hidden = false;
     }