prices: fold groceries and CS skins into one price tracker (/trackers/prices) with tabs

- tab registry in #lib/price-trackers (add a tab = route + entry + icon)
- groceries -> /trackers/prices/groceries (owner-only), CS prices -> /trackers/prices/cs (public)
- old /trackers/groceries/* and /projects/cs-prices/* redirect (301 GET, 308 POST) with query
- nav: one prices entry replaces groceries and skins; cyan price-tag icon

src/lib/tracker-icons.ts

@@ -189,6 +189,16 @@ export const trackerIcons: Record<string, TrackerIcon> = {
 			'M17.3 5H6.7a4 4 0 0 0-4 3.6C2.6 9.4 2 14.5 2 16a3 3 0 0 0 3 3c1 0 1.5-.5 2-1l1.4-1.4A2 2 0 0 1 9.8 16h4.4a2 2 0 0 1 1.4.6L17 18c.5.5 1 1 2 1a3 3 0 0 0 3-3c0-1.5-.6-6.6-.7-7.3A4 4 0 0 0 17.3 5z'
 		]
 	},
+	prices: {
+		from: '#22d3ee',
+		to: '#0e7490',
+		ink: WHITE,
+		// price tag
+		paths: [
+			'M12.6 2.6A2 2 0 0 0 11.2 2H4a2 2 0 0 0-2 2v7.2a2 2 0 0 0 .6 1.4l8.7 8.7a2.4 2.4 0 0 0 3.4 0l6.6-6.6a2.4 2.4 0 0 0 0-3.4z',
+			c(7.5, 7.5, 1.2)
+		]
+	},
 	skins: {
 		from: '#e879f9',
 		to: '#a21caf',