Harden the bulk auto confirm endpoint and the invite notification

Two issues found while reviewing the previous commits:

The bulk endpoint unwrapped the client supplied member id, so a single entry
without an id took the whole request down with a 500 and silently dropped the
confirmations of every other entry in the same call. Skip such an entry instead.
The manual `bulk_confirm_invite` has the same unwrap, that one is left alone
here.

`send_invite` announced the pending member right after saving the membership,
which is before the collections and groups of the invite are attached. An admin
client acts on that notification immediately, so it could confirm the member
while its access was still incomplete, and a failing collection or group
assignment would leave a confirmed member behind. The notification now happens
once the invite is fully applied.

src/api/core/organizations.rs

@@ -1125,9 +1125,6 @@ async fn send_invite(
         new_member.status = member_status;
         new_member.save(&conn).await?;
 
-        // With mail disabled an existing user is accepted right away, so there is no accept request later on
-        notify_pending_auto_confirm(&new_member, &conn, &nt).await;
-
         if CONFIG.mail_enabled() {
             let org_name = if let Some(org) = Organization::find_by_uuid(&org_id, &conn).await {
                 org.name
@@ -1193,6 +1190,11 @@ async fn send_invite(
             let mut group_entry = GroupUser::new(group_id.clone(), new_member.uuid.clone());
             group_entry.save(&conn).await?;
         }
+
+        // With mail disabled an existing user is accepted right away, so there is no accept request later on.
+        // This is the last step on purpose: an admin client may confirm the member the moment it is told
+        // about it, and by then the collections and groups of the invite have to be in place.
+        notify_pending_auto_confirm(&new_member, &conn, &nt).await;
     }
 
     Ok(())
@@ -1582,7 +1584,11 @@ async fn bulk_auto_confirm_members(
     match data.keys {
         Some(keys) => {
             for member in keys {
-                let member_id = member.id.unwrap();
+                // Never unwrap the id, this is client supplied and a missing one must not take the request down
+                let Some(member_id) = member.id else {
+                    error!("Ignoring a bulk auto confirm entry without a member id");
+                    continue;
+                };
                 let user_key = member.key.unwrap_or_default();
                 let err_msg = match auto_confirm_member_impl(&org_id, &member_id, &user_key, &headers, &conn, &nt).await
                 {