debug(missions): loud refresh diagnostic + drop disabled attr

The refresh button was suspected of being inert when loading is
somehow stuck true. Removes disabled and renders a bulletproof
click counter + loading state next to the icon:

  clicks:0 · updated 14:05:12 · idle

- clicks bumps SYNCHRONOUSLY in onClick before any await, so a
  non-zero counter proves the click event reaches the handler
- console.log fires alongside for devtools verification
- disabled={loading} removed; if load happens to hang, at least
  the user can click again to retry

Temporary scaffolding — will collapse once the root cause is clear.

frontend/src/components/dashboard/MissionCanvas.tsx

@@ -119,6 +119,7 @@ export function MissionCanvas({
   const [deleteBusy, setDeleteBusy] = useState(false);
   const [runs, setRuns] = useState<MissionRunSummary[]>([]);
   const [lastLoadedAt, setLastLoadedAt] = useState<Date | null>(null);
+  const [refreshClicks, setRefreshClicks] = useState(0);
 
   const load = useCallback(async () => {
     if (!selectedId) {
@@ -426,22 +427,26 @@ export function MissionCanvas({
                 {refining ? "Refining…" : "Refine"}
               </button>
             )}
-            {lastLoadedAt && (
-              <span
-                style={{
-                  fontSize: 10,
-                  color: "#6a6a72",
-                  fontFamily: mono,
-                }}
-                title={lastLoadedAt.toISOString()}
-              >
-                updated {lastLoadedAt.toLocaleTimeString()}
-              </span>
-            )}
+            <span
+              style={{
+                fontSize: 10,
+                color: refreshClicks > 0 ? "#5ec8d8" : "#6a6a72",
+                fontFamily: mono,
+              }}
+              title={lastLoadedAt ? lastLoadedAt.toISOString() : "not loaded yet"}
+            >
+              clicks:{refreshClicks} · {lastLoadedAt ? `updated ${lastLoadedAt.toLocaleTimeString()}` : "…"} · {loading ? "loading" : "idle"}
+            </span>
             <button
               type="button"
-              onClick={load}
-              disabled={loading}
+              onClick={() => {
+                setRefreshClicks((c) => c + 1);
+                console.log("[MissionCanvas] refresh clicked", {
+                  selectedId,
+                  loading,
+                });
+                void load();
+              }}
               title="Refresh"
               aria-label="Refresh"
               style={{ ...iconBtn, opacity: loading ? 0.6 : 1 }}