feat(psa): attribute posted notes to mapped CW member

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/api/endpoints/sessions.py

@@ -987,6 +987,21 @@ async def psa_post_to_ticket(
     )
     psa_connection = conn_result.scalar_one_or_none()
 
+    # Look up member mapping for attribution
+    from app.models.psa_member_mapping import PsaMemberMapping
+
+    member_id = None
+    if psa_connection:
+        mapping_result = await db.execute(
+            select(PsaMemberMapping).where(
+                PsaMemberMapping.psa_connection_id == psa_connection.id,
+                PsaMemberMapping.user_id == current_user.id,
+            )
+        )
+        mapping = mapping_result.scalar_one_or_none()
+        if mapping:
+            member_id = mapping.external_member_id
+
     # Post note
     try:
         provider = await get_provider_for_account(current_user.account_id, db)
@@ -994,6 +1009,7 @@ async def psa_post_to_ticket(
             ticket_id=session.psa_ticket_id,
             text=data.content,
             note_type=data.note_type,
+            member_id=member_id,
         )
         note_status = "success"
         external_note_id = note_result.id