fix(watchlist): remove actually removes on the second click

The two-click arm compared against the STATE variable, which each click's
handler captured at render time — a quick double-click read the pre-arm value
twice, so both clicks merely armed: the bin turned red and nothing was ever
deleted. The arm lives in a ref now, compared synchronously, and the window
grows to three seconds.

frontend/src/components/WatchlistTab.tsx

@@ -186,10 +186,23 @@ export function WatchlistTab({ spots, spotStatus, onSpotSelect, onSpotClick }: P
     } catch (e: any) { flash(String(e?.message ?? e), true); }
   };
 
+  // Armed through a REF, checked synchronously: the state variable is captured
+  // at render time, so a quick double-click read the pre-arm value twice and
+  // both clicks merely armed — the bin turned red and nothing was ever removed.
+  const removeArmRef = useRef('');
   const remove = async (call: string) => {
-    if (removeArm !== call) { setRemoveArm(call); window.setTimeout(() => setRemoveArm(''), 2500); return; }
+    if (removeArmRef.current !== call) {
+      removeArmRef.current = call;
+      setRemoveArm(call);
+      window.setTimeout(() => {
+        if (removeArmRef.current === call) { removeArmRef.current = ''; setRemoveArm(''); }
+      }, 3000);
+      return;
+    }
+    removeArmRef.current = '';
+    setRemoveArm('');
     try { await WatchlistRemove(call); await refresh(); }
-    catch (e: any) { setError(String(e?.message ?? e)); }
+    catch (e: any) { flash(String(e?.message ?? e), true); }
   };
 
   const isOnAir = (e: WLEntry): boolean =>