fix(campaign): mark excluded delivery as skipped

docs/CAMPAIGN_HANDBOOK.md

@@ -261,6 +261,13 @@ The delivery record should be able to identify:
   reconciliation note; and
 - actor/system trigger, timestamps, policy context, and corrections.
 
+An excluded recipient/message is a completed validation decision, not a
+pending delivery. Its SMTP and IMAP states are both `skipped`; it is counted and
+filterable separately from unattempted, failed, accepted, and append outcomes.
+No SMTP or IMAP attempt exists for such a row. If historical data contains
+actual transport evidence despite an exclusion marker, that evidence is
+preserved for audit and reconciliation rather than relabelled.
+
 ## Administration and policy
 
 ### Roles and permissions