Add WHOIS stats to status page with adaptive fetcher improvements

- Add WHOIS Fetcher card showing fresh/stale/never-fetched ASN counts
- Display hourly success/error counts and current fetch interval
- Increase max WHOIS rate to 1/sec (down from 10 sec minimum)
- Select random stale ASN instead of oldest for better distribution
- Add index on whois_updated_at for query performance
- Track success/error timestamps for hourly stats
- Add GetWHOISStats database method for freshness statistics

internal/database/interface.go

@@ -67,6 +67,7 @@ type Store interface {
 	// ASN WHOIS operations
 	GetNextStaleASN(ctx context.Context, staleThreshold time.Duration) (int, error)
 	UpdateASNWHOIS(ctx context.Context, update *ASNWHOISUpdate) error
+	GetWHOISStats(ctx context.Context, staleThreshold time.Duration) (*WHOISStats, error)
 
 	// AS and prefix detail operations
 	GetASDetails(asn int) (*ASN, []LiveRoute, error)