feat: UI redesign with park detail pages and ride status

Visual overhaul:
- Warmer color system with amber accent for Today, better text hierarchy
- Row hover highlighting, sticky column shadow on horizontal scroll
- Closed cells replaced with dot (·) instead of "Closed" text
- Regional grouping (Northeast/Southeast/Midwest/Texas & South/West)
- Two-row header with park count badge and WeekNav on separate lines
- Amber "Today" button in WeekNav when off current week
- Mobile card layout (< 1024px) with 7-day grid per park; table on desktop
- Skeleton loading state via app/loading.tsx

Park detail pages (/park/[id]):
- Month calendar view with ← → navigation via ?month= param
- Live ride status fetched from Six Flags API (cached 1h)
- Ride hours only shown when they differ from park operating hours
- Fallback to nearest upcoming open day when today is dropped by API,
  including cross-month fallback for end-of-month edge case

Data layer:
- Park type gains region field; parks.ts exports groupByRegion()
- db.ts gains getParkMonthData() for single-park month queries
- sixflags.ts gains scrapeRidesForDay() returning RidesFetchResult
  with rides, dataDate, isExact, and parkHoursLabel

Removed: CalendarGrid.tsx, MonthNav.tsx (dead code)

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

lib/db.ts

@@ -99,6 +99,42 @@ export function getDateRange(
   return result;
 }
 
+/**
+ * Returns scraped DayData for a single park for an entire month.
+ * Shape: { 'YYYY-MM-DD': DayData }
+ */
+export function getParkMonthData(
+  db: Database.Database,
+  parkId: string,
+  year: number,
+  month: number,
+): Record<string, DayData> {
+  const prefix = `${year}-${String(month).padStart(2, "0")}`;
+  const rows = db
+    .prepare(
+      `SELECT date, is_open, hours_label, special_type
+       FROM park_days
+       WHERE park_id = ? AND date LIKE ? || '-%'
+       ORDER BY date`
+    )
+    .all(parkId, prefix) as {
+    date: string;
+    is_open: number;
+    hours_label: string | null;
+    special_type: string | null;
+  }[];
+
+  const result: Record<string, DayData> = {};
+  for (const row of rows) {
+    result[row.date] = {
+      isOpen: row.is_open === 1,
+      hoursLabel: row.hours_label,
+      specialType: row.special_type,
+    };
+  }
+  return result;
+}
+
 /** Returns a map of parkId → boolean[] (index 0 = day 1) for a given month. */
 export function getMonthCalendar(
   db: Database.Database,