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/pages/SettingsHub.tsx

@@ -67,6 +67,7 @@ import { SnapshotSettings } from "../components/settings/SnapshotSettings";
 import { ReportSettings } from "../components/settings/ReportSettings";
 import { AiToolsSettings } from "../components/settings/AiToolsSettings";
 import { AgentInstructionsSettings } from "../components/settings/AgentInstructionsSettings";
+import { ArtifactsHubSettings } from "../components/settings/ArtifactsHubSettings";
 import { PricingSettings } from "../components/settings/PricingSettings";
 import { WorktreeVisibilitySettings } from "../components/settings/WorktreeVisibilitySettings";
 import { useAiTools } from "../hooks/useAiTools";
@@ -292,6 +293,8 @@ export function SettingsHub({ section }: { section?: string } = {}) {
         <div className="space-y-6">
           <AgentInstructionsSettings />
           <AiToolsSettings settingsHref={toolHref} />
+          {/* The Hub's install switch: server mode, an admin's (it hides itself). */}
+          <ArtifactsHubSettings />
         </div>
       ),
     },