feat: add Steam Reviews display API with caching

- Create lib/api/steam-reviews.ts with in-memory cache (1hr TTL)
- Proxy endpoint for fetching Steam reviews by game ID
- Supports offset/limit/language query params
- Registers route in API index and app router

app/api/[[...slugs]]/route.ts

@@ -27,6 +27,7 @@ import { gameStatsRoutes } from "@/lib/api/game-stats"
 import { gamesManualRoutes } from "@/lib/api/games-manual"
 import { compareRoutes } from "@/lib/api/compare"
 import { playabilityRoutes } from "@/lib/api/playability"
+import { steamReviewRoutes } from "@/lib/api/steam-reviews"
 import { gamesListingRoutes } from "@/lib/api/games-listing"
 import { steamgridProxyRoutes } from "@/lib/api/steamgrid-proxy"
 
@@ -104,6 +105,8 @@ export const app = new Elysia({ prefix: "/api" })
   .use(compareRoutes)
   // Playability
   .use(playabilityRoutes)
+  // Steam reviews
+  .use(steamReviewRoutes)
   // Root
   .get("/", () => ({
     name: "DeckyVault API",