Web Shell Workspaces overview panel (layer B2)

Issue: https://github.com/QwenLM/qwen-code/issues/10399 Design: docs/design/web-shell/web-shell-workspace-overview.md

Baseline

After #10407 (layer A) the sidebar shows per-workspace chips and a ⋮ menu, but there is no single place that lists every registered workspace with its health — the Projects section is the only aggregate view.

npm run build from the repository root.
node dist/cli.js serve --workspace <primary> --workspace <secondary> on loopback, with the secondary a git repository carrying local changes and one broken MCP server configured.

The Projects section ends with a "Manage workspaces…" row; clicking it replaces the chat view with the Workspaces panel (back arrow returns).
Embedders can add the workspacesOverview footer item; it is not part of the default footer. A sidebar locked to one workspace shows no entry.

One row per registered workspace (daemon-owned kind: 'live' runtimes are not listed):

Name (display name or folder basename) with primary / untrusted badges; full path with tooltip.
Sessions: active web-shell session count, n running / n need attention badges; — for untrusted rows. Counts refresh on a 30 s tick.
MCP: connected/configured plus n failed; — until the runtime is initialized (never 0/0 for an idle placeholder).
Branch: current branch plus n changed when the working tree is dirty (60 s cadence, same as the sidebar chip).
Last activity: relative time of the newest session update, — when the workspace has no sessions.

New task: starts a draft in that workspace (primary row targets the primary) and returns to the chat view.
Remove: only on trusted, removable, non-primary rows and only when the daemon advertises workspace_runtime_removal. Uses the same dialog and busy/force flow as the sidebar row (409 workspace_busy lists the activity and arms Force remove; removing the workspace the active session lives in stays blocked).
Add workspace in the toolbar opens the existing registration dialog (only with dynamic_workspace_registration).

packages/web-shell/client/components/workspaces/useWorkspaceRemoval.test.tsx (shared removal flow: busy→force, mismatch, blocked force, error path)
packages/web-shell/client/components/workspaces/WorkspacesOverviewPanel.test.tsx (rows, badges, counts, unknown-not-zero, untrusted gating, actions)
packages/web-shell/client/components/sidebar/WebShellSidebar.workspace-removal.test.tsx (sidebar flow on the shared hook + the Manage workspaces entry)
packages/web-shell/client/App.test.tsx (panel opens from the sidebar)
packages/web-shell/client/e2e/web-shell.workspaces-panel.spec.ts