chore: v2.8.21 — update progress steps, clone in background, extra SSH keys inline, today's spend

- Plugin update reports its running step (plugin-update-progress.json →
  plugin_update_progress); a hidden update or clone leaves a progress chip.
- Clone here can run in the background.
- Git identity: extra SSH keys are added inline per host (no More keys tab).
- Users: spend today (viewer's local day, ?tz_offset=).
- Prettier on the files touched since v2.8.20.

server/__tests__/server-mode-users.test.js

@@ -78,6 +78,10 @@ describe("staff views", () => {
     assert.equal(mia.workspaces, 1);
     assert.equal(mia.sessions, 1);
     assert.ok(mia.last7d.cost > 0 && mia.last30d.cost >= mia.last7d.cost);
+    // This hour's spend is today's in every timezone.
+    assert.equal(mia.today.cost, mia.last7d.cost);
+    const east = await call("/api/users?tz_offset=-840", admin);
+    assert.equal(east.body.users.find((u) => u.username === "mia").today.tokens, mia.today.tokens);
     assert.ok(!JSON.stringify(r.body).includes("scrypt"), "no password hash");
     assert.equal((await call("/api/users", await login("ana", "analyst-pass-1"))).status, 200);
     const member = await call("/api/users", await login("mia", "member-pass-1"));