fix(cost): bill a session outside every workspace to its Linux account's user

A script's claude -p in a temp folder (the SG Flow eval runner strips the
pane's env) had no workspace, so its spend reached nobody's Today, the Users
page or a spend quota — ~$57 of a $74 day was missing from the status bar.

sessions.account records the Linux account a session ran as (the hook's
peer uid, else its folder for poller-made and old rows); a session no
workspace owns is owned by that account's user — a member's to them, the
host's to the admin ticked 'Owns this server's host account' (or the only
admin). Workspace ownership still wins.

server/index.js

@@ -873,7 +873,9 @@ function startBackgroundServices() {
     if (poolTimer.unref) poolTimer.unref();
   }
   // Server mode's spend quotas (user-quota.js): who is over theirs now, the
-  // flag files their hooks read, the panes no hook can stop. Off with
+  // flag files their hooks read, the panes no hook can stop — after giving
+  // the sessions no hook made their Linux account (session-account.js), so a
+  // poller's session is billed to someone too. Off with
   // DASHBOARD_QUOTA_SWEEP_MS=0; a no-op in local mode.
   const QUOTA_SWEEP_MS = Number(process.env.DASHBOARD_QUOTA_SWEEP_MS ?? 60_000);
   if (
@@ -883,6 +885,7 @@ function startBackgroundServices() {
   ) {
     const quotaSweep = () => {
       try {
+        require("./lib/session-account").stampFromFolders();
         require("./lib/user-quota").sweep();
       } catch (err) {
         console.warn("user quota sweep failed:", err.message);