Add IP information API with background WHOIS fetcher

- Add /ip and /ip/{addr} JSON endpoints returning comprehensive IP info
- Include ASN, netblock, country code, org name, abuse contact, RIR data
- Extend ASN schema with WHOIS fields (country, org, abuse contact, etc)
- Create background WHOIS fetcher for rate-limited ASN info updates
- Store raw WHOIS responses for debugging and data preservation
- Queue on-demand WHOIS lookups when stale data is requested
- Refactor handleIPInfo to serve all IP endpoints consistently

internal/database/interface.go

@@ -61,6 +61,12 @@ type Store interface {
 	// IP lookup operations
 	GetASInfoForIP(ip string) (*ASInfo, error)
 	GetASInfoForIPContext(ctx context.Context, ip string) (*ASInfo, error)
+	GetIPInfo(ip string) (*IPInfo, error)
+	GetIPInfoContext(ctx context.Context, ip string) (*IPInfo, error)
+
+	// ASN WHOIS operations
+	GetNextStaleASN(ctx context.Context, staleThreshold time.Duration) (int, error)
+	UpdateASNWHOIS(ctx context.Context, update *ASNWHOISUpdate) error
 
 	// AS and prefix detail operations
 	GetASDetails(asn int) (*ASN, []LiveRoute, error)