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>

components/WeekNav.tsx

@@ -3,8 +3,9 @@
 import { useRouter } from "next/navigation";
 
 interface WeekNavProps {
-  weekStart: string; // YYYY-MM-DD (Sunday)
+  weekStart: string;   // YYYY-MM-DD (Sunday)
   weekDates: string[]; // 7 dates YYYY-MM-DD
+  isCurrentWeek: boolean;
 }
 
 const MONTHS = [
@@ -29,27 +30,43 @@ function shiftWeek(weekStart: string, delta: number): string {
   return d.toISOString().slice(0, 10);
 }
 
-export function WeekNav({ weekStart, weekDates }: WeekNavProps) {
+export function WeekNav({ weekStart, weekDates, isCurrentWeek }: WeekNavProps) {
   const router = useRouter();
   const nav = (delta: number) =>
     router.push(`/?week=${shiftWeek(weekStart, delta)}`);
 
   return (
-    <div style={{ display: "flex", alignItems: "center", gap: 16 }}>
+    <div style={{ display: "flex", alignItems: "center", gap: 8 }}>
       <button
         onClick={() => nav(-1)}
         aria-label="Previous week"
-        style={btnStyle}
+        style={navBtnStyle}
+        onMouseOver={(e) => Object.assign((e.target as HTMLElement).style, navBtnHover)}
+        onMouseOut={(e) => Object.assign((e.target as HTMLElement).style, navBtnStyle)}
       >
         ←
       </button>
 
+      {!isCurrentWeek && (
+        <button
+          onClick={() => router.push("/")}
+          aria-label="Jump to current week"
+          style={todayBtnStyle}
+          onMouseOver={(e) => Object.assign((e.target as HTMLElement).style, todayBtnHover)}
+          onMouseOut={(e) => Object.assign((e.target as HTMLElement).style, todayBtnStyle)}
+        >
+          Today
+        </button>
+      )}
+
       <span style={{
-        fontSize: "1.1rem",
+        fontSize: "1rem",
         fontWeight: 600,
         color: "var(--color-text)",
-        minWidth: 220,
+        minWidth: 200,
         textAlign: "center",
+        letterSpacing: "-0.01em",
+        fontVariantNumeric: "tabular-nums",
       }}>
         {formatLabel(weekDates)}
       </span>
@@ -57,7 +74,9 @@ export function WeekNav({ weekStart, weekDates }: WeekNavProps) {
       <button
         onClick={() => nav(1)}
         aria-label="Next week"
-        style={btnStyle}
+        style={navBtnStyle}
+        onMouseOver={(e) => Object.assign((e.target as HTMLElement).style, navBtnHover)}
+        onMouseOut={(e) => Object.assign((e.target as HTMLElement).style, navBtnStyle)}
       >
         →
       </button>
@@ -65,7 +84,7 @@ export function WeekNav({ weekStart, weekDates }: WeekNavProps) {
   );
 }
 
-const btnStyle: React.CSSProperties = {
+const navBtnStyle: React.CSSProperties = {
   padding: "6px 14px",
   borderRadius: 6,
   border: "1px solid var(--color-border)",
@@ -74,4 +93,47 @@ const btnStyle: React.CSSProperties = {
   cursor: "pointer",
   fontSize: "1rem",
   lineHeight: 1,
+  transition: "background 150ms ease, border-color 150ms ease, color 150ms ease",
+};
+
+const navBtnHover: React.CSSProperties = {
+  padding: "6px 14px",
+  borderRadius: 6,
+  border: "1px solid var(--color-text-dim)",
+  background: "var(--color-surface-2)",
+  color: "var(--color-text-secondary)",
+  cursor: "pointer",
+  fontSize: "1rem",
+  lineHeight: 1,
+  transition: "background 150ms ease, border-color 150ms ease, color 150ms ease",
+};
+
+const todayBtnStyle: React.CSSProperties = {
+  padding: "5px 12px",
+  borderRadius: 6,
+  border: "1px solid var(--color-accent-muted)",
+  background: "transparent",
+  color: "var(--color-accent)",
+  cursor: "pointer",
+  fontSize: "0.75rem",
+  fontWeight: 600,
+  letterSpacing: "0.04em",
+  textTransform: "uppercase",
+  lineHeight: 1,
+  transition: "background 150ms ease, color 150ms ease",
+};
+
+const todayBtnHover: React.CSSProperties = {
+  padding: "5px 12px",
+  borderRadius: 6,
+  border: "1px solid var(--color-accent-muted)",
+  background: "var(--color-accent-muted)",
+  color: "var(--color-accent-text)",
+  cursor: "pointer",
+  fontSize: "0.75rem",
+  fontWeight: 600,
+  letterSpacing: "0.04em",
+  textTransform: "uppercase",
+  lineHeight: 1,
+  transition: "background 150ms ease, color 150ms ease",
 };