feat: ship waterfall receiver overhaul and platform mode updates

static/css/modes/rfheatmap.css

@@ -0,0 +1,44 @@
+/* RF Heatmap Mode Styles */
+
+.rfhm-map-container {
+    flex: 1;
+    min-height: 0;
+    position: relative;
+}
+
+#rfheatmapMapEl {
+    width: 100%;
+    height: 100%;
+}
+
+.rfhm-overlay {
+    position: absolute;
+    top: 8px;
+    right: 8px;
+    z-index: 450;
+    display: flex;
+    flex-direction: column;
+    gap: 4px;
+    pointer-events: none;
+}
+
+.rfhm-stat-chip {
+    background: rgba(0,0,0,0.75);
+    border: 1px solid rgba(255,255,255,0.15);
+    border-radius: 6px;
+    padding: 4px 8px;
+    font-family: var(--font-mono, monospace);
+    font-size: 10px;
+    color: var(--accent-cyan, #4aa3ff);
+    pointer-events: none;
+    backdrop-filter: blur(4px);
+}
+
+.rfhm-recording-pulse {
+    animation: rfhm-rec 1s ease-in-out infinite;
+}
+
+@keyframes rfhm-rec {
+    0%, 100% { opacity: 1; }
+    50% { opacity: 0.3; }
+}