refactor: make frontend a pure presentation layer fetching from backend API

Server components now fetch composed data from the backend instead of
directly querying SQLite and external APIs. Removes better-sqlite3
dependency from the frontend entirely.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

components/HomePageClient.tsx

@@ -8,7 +8,7 @@ import { WeekNav } from "./WeekNav";
 import { Legend } from "./Legend";
 import { EmptyState } from "./EmptyState";
 import { PARKS, groupByRegion } from "@/lib/parks";
-import type { DayData } from "@/lib/db";
+import type { DayData } from "@/lib/types";
 
 const REFRESH_INTERVAL_MS = 2 * 60 * 1000; // 2 minutes
 const OPEN_REFRESH_BUFFER_MS = 30_000;      // 30s after opening time before hitting the API