feat: workspace aliases, tab groups of split panes, native path picker (v2.1.0)

- /api/workspaces and `agenthub workspace(s)` / `--workspace` as aliases of
  /api/lanes and `agenthub lanes` / `--lane`; old names print one stderr note.
  REPL `help lanes|workspace|workspaces` resolves through the aliases.
- A workspace holds up to ten sessions (slots 0-9); every console tab is a
  group of 1-4 split panes (PaneGroups, agenthub.workspace.paneLayout);
  parseGroups keeps the stored active tab when an earlier one is dropped.
- Browse button beside path fields: POST /api/lanes/pick-path opens the OS
  picker on the server's desktop — loopback only and no forwarding header
  (EREMOTE), a display failure is ENODIALOG not a Cancel, the dialog is
  killed when the request closes, a folder field falls back to the in-app
  browser on any failure.
- Changes rail counts chip, image viewer (/git/raw), status bar session
  counts and per-day cost (`date=` on /api/pricing/cost).
- /agenthub-open and /agenthub-doctor run from the INSTALLED build
  (supersededBy), doctor offers fixes behind two confirmations; plugin-open
  treats a locked bootstrap as non-fatal.
- New-terminal shell waits for the first attach (issue #55).
- repo-onboarding / debug-live-issue skills removed.
- OpenAPI: pick-path, lane/date on /pricing/cost, tool on /run/history,
  /api/workspaces mount.

client/src/components/workflows/__tests__/LanePipelinePanel.test.tsx

@@ -151,7 +151,7 @@ describe("LanePipelinePanel", () => {
     statsMock.mockResolvedValue({ pipelines: [], lanes: [] });
     render(<LanePipelinePanel />);
 
-    expect(await screen.findByText(/agenthub lanes add/)).toBeInTheDocument();
+    expect(await screen.findByText(/agenthub workspace add/)).toBeInTheDocument();
   });
 
   it("refetches narrowed to the lane picked, and falls back to a cwd for an untitled one", async () => {
@@ -181,7 +181,7 @@ describe("LanePipelinePanel", () => {
     // the whole subtree, so a handle grabbed before it is already detached.
     await waitFor(() => expect(screen.queryByTestId("pipeline-stat-plan")).not.toBeInTheDocument());
     expect(screen.getByTestId("pipeline-stats-lane-picker")).toBeInTheDocument();
-    expect(screen.queryByText(/agenthub lanes add/)).not.toBeInTheDocument();
+    expect(screen.queryByText(/agenthub workspace add/)).not.toBeInTheDocument();
   });
 
   it("surfaces a failed fetch", async () => {