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/lib/laneOrderStorage.ts

@@ -1,7 +1,9 @@
 /**
  * @file laneOrderStorage.ts
- * @description Persists the Workspace lane strip's user-chosen card order to
- * localStorage, the same read/validate/fallback convention as useTheme.ts.
+ * @description Persists the sidebar's user-chosen workspace order to
+ * localStorage, the same read/validate/fallback convention as useTheme.ts, and
+ * holds the drag-to-reorder math the sidebar and the console tab bar share
+ * (the tab bar's own order lives with its tabs, `lib/paneLayout.ts`).
  *
  * The order lives in the browser rather than the lanes table on purpose: it is
  * a per-viewer preference, and nothing
@@ -66,3 +68,20 @@ export function moveLane(ids: number[], from: number, to: number): number[] {
   next.splice(to, 0, ...next.splice(from, 1));
   return next;
 }
+
+/** Where a drop lands: before the first item whose middle (`mids`, on the
+ *  drag axis) lies past the pointer, else at the end. Gaps between items —
+ *  a workspace's session list, the space between two tabs — count too. */
+export function insertionIndex(mids: number[], pos: number): number {
+  const i = mids.findIndex((m) => pos < m);
+  return i === -1 ? mids.length : i;
+}
+
+/** Moves the item at `from` to just before insertion point `before`. */
+export function moveBefore<T>(ids: T[], from: number, before: number): T[] {
+  if (from < 0 || from >= ids.length || before < 0 || before > ids.length) return ids;
+  if (before === from || before === from + 1) return ids;
+  const next = [...ids];
+  next.splice(before > from ? before - 1 : before, 0, ...next.splice(from, 1));
+  return next;
+}