Fog of war: underground is black until the bot has seen it (t8)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/ui/settings.js

@@ -45,6 +45,7 @@ const SET_TABS = {
     { html: () => controlsHtml() },
   ],
   Game: [
+    { k: 'fog', label: 'Fog of war', d: 'Places you have not seen yet are black. Off shows the whole world.', type: 'toggle' },
     { k: 'cardSeconds', label: 'Discovery cards', d: 'How long a card stays when you find or make something new. Everything is also in the notebook.', type: 'select', opts: [[0, 'Off'], [5, '5 seconds'], [9, '9 seconds'], [15, '15 seconds'], [-1, 'Until I close them']] },
     { k: 'autosave', label: 'Autosave', type: 'select', opts: [[0, 'Off'], [1, 'Every minute'], [3, 'Every 3 minutes'], [5, 'Every 5 minutes'], [10, 'Every 10 minutes']] },
     { k: 'save', label: 'Save', d: 'Saves to this browser.', type: 'button', text: 'Save now', fn: () => saveWorld('main'), ingame: true },