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/title.ts

@@ -36,7 +36,9 @@ export function getTitle(path: string, environment: SiteEnvironment = null): str
 		'/projects/animaldex/register': 'Log a sighting',
 		'/projects/animaldex/admin': 'Animaldex admin',
 		'/projects/derby': 'Derby Lens',
-		'/projects/cs-prices': 'CS Prices',
+		'/trackers/prices': 'Prices',
+		'/trackers/prices/cs': 'CS Prices',
+		'/trackers/prices/groceries': 'Groceries',
 		'/trackers/games': 'Game Tracker',
 		'/projects/language-learner': 'Language Learner',
 		'/projects/spotify-beatmap-finder': 'osu! map finder',