feat: v2.8.0 — Artifacts uploads and plugin links, console tab combos, account avatars

- Artifacts hub: upload a file from the computer; make a skill by uploading a
  Markdown file, files, a folder or a .zip/.skill, or by writing it in the
  dialog; add plugins by picking from the list a marketplace link answers
  (POST /api/artifacts/plugin/inspect); Settings → AI tools → Artifacts Hub.
- Console tabs are combos of up to four split panes (ConsoleTabs, PaneGrid).
- Accounts: an own avatar (PUT/DELETE /api/me/avatar, raster only, ≤ 1 MB,
  <data dir>/avatars/), shown with name and role at the sidebar's foot and on
  the workspace owner groups (GET /api/users/:id/avatar, owner_avatar_at).
- Users page: per-user storage (GET /api/users/storage, measured in a worker)
  and account-pool spend/tokens per account (server/lib/pool-usage.js).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

client/src/components/users/__tests__/AccountPoolCard.test.tsx

@@ -40,6 +40,8 @@ const POOL: AccountPool = {
       livePanes: 2,
       spend5h: 1.5,
       spend7d: 12,
+      tokens5h: 250_000,
+      tokens7d: 3_400_000,
       quotaPercent: 42,
       full: false,
     },
@@ -52,6 +54,8 @@ const POOL: AccountPool = {
       livePanes: 0,
       spend5h: 0,
       spend7d: 0,
+      tokens5h: 0,
+      tokens7d: 0,
       quotaPercent: null,
       full: false,
     },
@@ -82,6 +86,8 @@ describe("AccountPoolCard", () => {
     expect(await screen.findByText("team-1")).toBeInTheDocument();
     expect(screen.getByText("cx-1")).toBeInTheDocument();
     expect(screen.getByText("42%")).toBeInTheDocument();
+    expect(screen.getByText("250.0K tokens")).toBeInTheDocument();
+    expect(screen.getByText("$12.00 · 3.4M tokens in 7 days")).toBeInTheDocument();
     expect(screen.getByText("team1@example.com")).toBeInTheDocument();
     expect(screen.queryByRole("button", { name: /add account/i })).toBeNull();
     expect(screen.queryByRole("button", { name: /remove/i })).toBeNull();