Add mock heart rate simulator flow

tools/mock-gps-sim/public/style.css

@@ -2,24 +2,30 @@
   box-sizing: border-box;
 }
 
+html,
 body {
+  height: 100%;
   margin: 0;
   font-family: "Segoe UI", "PingFang SC", sans-serif;
   background: #edf3ea;
   color: #163126;
+  overflow: hidden;
 }
 
 .layout {
   display: grid;
   grid-template-columns: 400px 1fr;
-  min-height: 100vh;
+  height: 100vh;
+  overflow: hidden;
 }
 
 .panel {
+  height: 100vh;
   padding: 20px;
   background: rgba(250, 252, 248, 0.96);
   border-right: 1px solid rgba(22, 49, 38, 0.08);
   overflow-y: auto;
+  overscroll-behavior: contain;
 }
 
 .panel__header h1 {
@@ -221,7 +227,9 @@ body {
 }
 
 .map-shell {
-  min-height: 100vh;
+  position: relative;
+  height: 100vh;
+  overflow: hidden;
 }
 
 #map {