Flag LiveTrack sessions whose map Garmin no longer serves

Ended sessions past the ~24h Garmin appears to keep a live-track page
around for get verified once at app startup and, once confirmed dead,
flagged so the panel greys them out instead of only failing after a
click. Already-flagged sessions are skipped on later startups so this
doesn't keep re-hitting Garmin for the same dead session.

public/css/style.css

@@ -781,6 +781,11 @@ html, body {
   cursor: wait;
 }
 
+.livetrack-panel__row:disabled {
+  opacity: 0.5;
+  cursor: default;
+}
+
 .livetrack-panel__label {
   flex: 1;
   min-width: 0;

public/js/livetrack.js

@@ -76,15 +76,18 @@ export class LiveTrackPanelControl {
       return;
     }
 
-    sessions.forEach(({ id, received_at, summary }) => {
+    sessions.forEach(({ id, received_at, summary, map_available }) => {
       const li = document.createElement("li");
       li.className = "livetrack-panel__item";
 
+      const unavailable = map_available === false;
+
       const button = document.createElement("button");
       button.type = "button";
       button.className = "livetrack-panel__row";
       button.classList.toggle("active", id === this._activeSessionId);
-      button.title = id;
+      button.disabled = unavailable;
+      button.title = unavailable ? "Garmin no longer serves this session's map" : id;
 
       const labelSpan = document.createElement("span");
       labelSpan.className = "livetrack-panel__label";
@@ -100,7 +103,7 @@ export class LiveTrackPanelControl {
       } else {
         button.append(labelSpan, timeSpan);
       }
-      button.addEventListener("click", () => this._toggleTrack(id, button));
+      if (!unavailable) button.addEventListener("click", () => this._toggleTrack(id, button));
       li.appendChild(button);
       this._list.appendChild(li);
     });