feat(acl): add reason field to ACL logging for decision tracking

Add a reason parameter throughout the ACL system to track and log why
each IP was allowed or denied. This provides better visibility into
ACL decisions by recording specific reasons such as "allowed by
allow_local rule", "blocked by deny rule: [rule]", or "deny by default".

Changes include:
- Add reason field to checkCache and ipLog structs
- Update LogACL interface and implementations to accept reason
- Generate descriptive reasons for all ACL decision paths
- Include reason in console log output

internal/logging/accesslog/formatter.go

@@ -171,7 +171,7 @@ func (f ACLLogFormatter) LogACLZeroLog(logger *zerolog.Logger, info *maxmind.IPI
 	event.Send()
 }
 
-func (f ConsoleACLFormatter) LogACLZeroLog(logger *zerolog.Logger, info *maxmind.IPInfo, blocked bool) {
+func (f ConsoleACLFormatter) LogACLZeroLog(logger *zerolog.Logger, info *maxmind.IPInfo, blocked bool, reason string) {
 	event := logger.Info()
 	if info.City != nil {
 		if isoCode := info.City.Country.IsoCode; isoCode != "" {
@@ -186,6 +186,10 @@ func (f ConsoleACLFormatter) LogACLZeroLog(logger *zerolog.Logger, info *maxmind
 		action = "denied"
 	}
 
+	if reason != "" {
+		event.Str("reason", reason)
+	}
+
 	// NOTE: zerolog will append a newline to the buffer
 	event.Msgf("request %s from %s", action, info.Str)
 }