feat(ui): explain operator workspace choices

src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css

@@ -2949,7 +2949,8 @@ button.is-active {
   font-weight: 700;
   letter-spacing: 0.04em;
   text-transform: uppercase;
-  overflow: hidden;
+  overflow: visible;
+  position: relative;
 }
 .operator-layout-picker::before { content: "Layout"; }
 .operator-layout-picker select {
@@ -2967,6 +2968,36 @@ button.is-active {
 }
 .operator-layout-picker:focus-within { border-color: var(--accent-green); box-shadow: 0 0 0 2px color-mix(in srgb, var(--accent-green) 20%, transparent); }
 .operator-layout-picker select:focus-visible { outline: 0; }
+.operator-layout-description {
+  position: absolute;
+  top: calc(100% + 0.35rem);
+  left: 0;
+  z-index: 25;
+  width: max-content;
+  max-width: min(22rem, calc(100vw - 2rem));
+  padding: 0.35rem 0.55rem;
+  border: 1px solid var(--border-light);
+  border-radius: var(--radius-sm);
+  background: var(--card-bg);
+  color: var(--text-muted);
+  box-shadow: 0 8px 24px color-mix(in srgb, #000 28%, transparent);
+  font-size: var(--fs-xs);
+  font-weight: 500;
+  letter-spacing: 0;
+  line-height: 1.35;
+  text-transform: none;
+  opacity: 0;
+  transform: translateY(-0.2rem);
+  visibility: hidden;
+  pointer-events: none;
+  transition: opacity var(--dur-fast) var(--ease-out), transform var(--dur-fast) var(--ease-out), visibility var(--dur-fast);
+}
+.operator-layout-picker:hover .operator-layout-description,
+.operator-layout-picker:focus-within .operator-layout-description {
+  opacity: 1;
+  transform: none;
+  visibility: visible;
+}
 .advanced-radio-controls {
   margin-top: var(--space-3);
   border: 1px solid color-mix(in srgb, var(--border-light) 75%, transparent);

src/trx-client/trx-frontend/trx-frontend-http/assets/web/ui-core.js

@@ -126,10 +126,10 @@
   };
 
   const layouts = {
-    compact: { label: "Compact", advanced: false, preferredTab: "main" },
+    compact: { label: "Compact", description: "Essential tuning and audio controls", advanced: false, preferredTab: "main" },
-    broadcast: { label: "Broadcast", advanced: false, preferredTab: "main", capability: "broadcast" },
+    broadcast: { label: "Broadcast", description: "WFM, RDS, stereo and interference monitoring", advanced: false, preferredTab: "main", capability: "broadcast" },
-    digital: { label: "Digital", advanced: false, preferredTab: "digital-modes", capability: "digital" },
+    digital: { label: "Digital", description: "Decoder status, messages and background decoding", advanced: false, preferredTab: "digital-modes", capability: "digital" },
-    full: { label: "Full controls", advanced: true, preferredTab: "main" },
+    full: { label: "Full controls", description: "Every control supported by the selected rig", advanced: true, preferredTab: "main" },
   };
   const layoutCapabilities = { broadcast: false, digital: false };
 
@@ -166,6 +166,8 @@
     localStorage.setItem("trxOperatorLayout", document.body.dataset.operatorLayout);
     const details = document.getElementById("advanced-radio-controls");
     if (details) details.open = layout.advanced;
+    const description = document.getElementById("operator-layout-description");
+    if (description) description.textContent = layout.description;
     if (options.navigate && typeof window.navigateToTab === "function") {
       window.navigateToTab(layout.preferredTab);
     }
@@ -176,7 +178,7 @@
     if (actions && !document.getElementById("operator-layout-select")) {
       const label = document.createElement("label");
       label.className = "operator-layout-picker";
-      label.innerHTML = '<span class="visually-hidden">Operator layout</span><select id="operator-layout-select" aria-label="Operator layout"></select>';
+      label.innerHTML = '<span class="visually-hidden">Operator layout</span><select id="operator-layout-select" aria-label="Operator layout" aria-describedby="operator-layout-description"></select><span id="operator-layout-description" class="operator-layout-description"></span>';
       const select = label.querySelector("select");
       const savedLayout = localStorage.getItem("trxOperatorLayout") || "compact";
       actions.insertBefore(label, actions.firstChild);