feat(config): add pool_domain and upgrade dependencies

- Add configurable pool_domain with pool.ntp.org default
- Update Go from 1.23.5 to 1.24.0
- Update golang.org/x/* dependencies
- Add enumer and accessory as tool dependencies
- Update goreleaser to v2.12.3

config/config.go

@@ -39,6 +39,8 @@ type Config struct {
 	webHostnames []string
 	webTLS       bool
 
+	poolDomain string `accessor:"getter"`
+
 	valid bool `accessor:"getter"`
 }
 
@@ -52,6 +54,7 @@ type Config struct {
 //   - web_hostname: Comma-separated web hostnames (first becomes primary)
 //   - manage_tls: Management interface TLS setting
 //   - web_tls: Web interface TLS setting
+//   - pool_domain: NTP pool domain (default: pool.ntp.org)
 func New() *Config {
 	c := Config{}
 	c.deploymentMode = os.Getenv("deployment_mode")
@@ -69,6 +72,11 @@ func New() *Config {
 	c.manageTLS = parseBool(os.Getenv("manage_tls"))
 	c.webTLS = parseBool(os.Getenv("web_tls"))
 
+	c.poolDomain = os.Getenv("pool_domain")
+	if c.poolDomain == "" {
+		c.poolDomain = "pool.ntp.org"
+	}
+
 	return &c
 }