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/openapi-extra/override-pricing-alerts.js

@@ -335,6 +335,27 @@ module.exports = {
               "for all sources. Narrows the aggregate cost to the given origins.",
             example: "local",
           },
+          {
+            name: "lane",
+            in: "query",
+            required: false,
+            schema: { type: "integer" },
+            description:
+              "Only the sessions this workspace owns — the same rule as " +
+              "GET /api/sessions?lane=. 400 INVALID_INPUT when not an id.",
+            example: 5,
+          },
+          {
+            name: "date",
+            in: "query",
+            required: false,
+            schema: { type: "string", format: "date" },
+            description:
+              "Only that local day (YYYY-MM-DD, in `tz_offset`'s timezone): the " +
+              "total and breakdown count the tokens spent that day. 400 " +
+              "INVALID_INPUT for any other shape.",
+            example: "2026-10-06",
+          },
         ],
         responses: {
           200: {