feat(cluster): chase switches for POTA and SOTA

An operator who does not chase parks does not want NEW POTA shouting from every
activator spot. Two switches (Settings → DX Cluster, on by default): off, the
marker is withdrawn at the display layer — applySpotDisplay, the same chokepoint
the grid, the band map and the filter read through — so the badge, the colour,
the filter chip and the reference column all go quiet together, and a new-band +
new-POTA spot reads NEW BAND alone. The facts keep being computed; only the
telling stops, so ticking the box back on needs no rescan.

frontend/src/lib/uiPref.ts

@@ -42,6 +42,8 @@ const PORTABLE_KEYS = [
   'opslog.clusterModeFilter', 'opslog.clusterSearch', 'opslog.clusterHideWorked',
   'opslog.distanceMiles', // distances shown in statute miles rather than km
   'opslog.iaruRegion',    // IARU region (1/2/3) — band edges and segments on the band maps
+  'opslog.chasePota',     // show POTA references and the NEW POTA marker on spots
+  'opslog.chaseSota',     // show SOTA references on spots
   'opslog.activeTab',     // last selected tab
   'opslog.mainSplit',    // Main tab: width share of the left pane (percent) — legacy, read once to seed mainShares
   'opslog.mainShares',   // Main tab: column shares per column count, as {2:[..],3:[..],4:[..]}