fix: set account_id on PsaPostLog in psa_post_to_ticket (missed third write path); fix get_admin_db docstring

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/api/endpoints/sessions.py

@@ -1102,6 +1102,7 @@ async def psa_post_to_ticket(
     # Log to audit trail
     log_entry = PsaPostLog(
         session_id=session.id,
+        account_id=session.account_id,
         psa_connection_id=psa_connection.id if psa_connection else None,
         ticket_id=session.psa_ticket_id,
         note_type=data.note_type,

backend/app/core/admin_database.py

@@ -27,7 +27,7 @@ _admin_session_factory = async_sessionmaker(
 
 
 async def get_admin_db() -> AsyncGenerator[AsyncSession, None]:
-    """Yield an admin DB session (BYPASSRLS). Use only on /admin/* endpoints."""
+    """Yield an admin DB session (BYPASSRLS). See module docstring for approved use cases."""
     async with _admin_session_factory() as session:
         try:
             yield session