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.

server/index.js

@@ -130,9 +130,13 @@ function createApp() {
   app.use("/api/git-credentials", gitCredentialsRouter);
   app.use("/api/ai-tools", aiToolsRouter);
   app.use("/api/run", runRouter);
-  // Before the lanes router, whose `/:id/:action` would otherwise see these.
-  app.use("/api/lanes", laneSourcesRouter);
-  app.use("/api/lanes", lanesRouter);
+  // `/api/workspaces` is the same router under the UI's word; `/api/lanes`
+  // stays for every client and script that already names it (whether it ever
+  // goes is step 4c of docs/plans/workspace-rename/README.md, default keep).
+  // Sources first: the lanes router's `/:id/:action` would otherwise see them.
+  const LANE_MOUNTS = ["/api/lanes", "/api/workspaces"];
+  app.use(LANE_MOUNTS, laneSourcesRouter);
+  app.use(LANE_MOUNTS, lanesRouter);
   app.use("/api/projects", projectsRouter);
   app.use("/api/locks", locksRouter);
   app.use("/api/pets", petsRouter);