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/lib/pty-attach.js

@@ -14,10 +14,10 @@
 const fs = require("fs");
 const tmux = require("./tmux");
 
-const RUN_ID_RE = /^agenthub-lane-\d+(?:-[1-3])?$/;
+const RUN_ID_RE = /^agenthub-lane-\d+(?:-[1-9])?$/;
 
 /**
- * Reject anything that isn't exactly `agenthub-lane-<digits>[-<1-3>]` before it can ever
+ * Reject anything that isn't exactly `agenthub-lane-<digits>[-<1-9>]` before it can ever
  * reach a tmux/PTY command — the trust boundary for this WS path, since a
  * validated runId is the only thing standing between an authenticated WS
  * client and naming an arbitrary session on the host.