feat(freeradius): set client-specific accounting intervals

- Set 60s interim updates for engineers
- Set 300s interim updates for devices

files/sites-available/default

@@ -807,10 +807,22 @@ post-auth {
 
 		update reply {
 			Session-Timeout := 3600
+			Acct-Interim-Interval := 60
 		}
 
 		sqlippool
 	}
+
+	#
+	# Devices → fixed IP
+	# authorize --> post-auth: reuse Tmp-String-1
+	elsif (&control:Tmp-String-1 == "device") {
+
+		update reply {
+			Acct-Interim-Interval := 300
+		}
+	}
+
     #
 	# HARD CHECK: must have IP
 	#