ui: separate trackers from projects; keep header dropdown on top

- /trackers index, Trackers section on the homepage and in the header nav;
  /projects lists only projects (tracker URLs unchanged)
- header is its own z-50 layer and <main> is isolated, so maps, charts and
  sticky tables no longer paint over the nav dropdowns

src/lib/seo.ts

@@ -32,9 +32,14 @@ const publicPages: Record<string, { title: string; description: string }> = {
 	'/projects': {
 		title: 'Projects',
 		description:
-			'Software projects by Stan Runge, including Game Tracker, Animaldex and Derby Lens.'
+			'Software projects by Stan Runge, including osu! map finder, Derby Lens and Language Learner.'
 	},
 	'/blog': { title: 'Blog', description: 'Articles and notes by Stan Runge.' },
+	'/trackers': {
+		title: 'Trackers',
+		description:
+			'Stan Runge’s trackers: games, money, houses, Counter-Strike prices, Animaldex and lists.'
+	},
 	'/lists': { title: 'Lists', description: 'Lists collected and maintained by Stan Runge.' },
 	'/projects/game-tracker': {
 		title: 'Game Tracker',