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/ImportHistory.tsx

@@ -81,6 +81,7 @@ import {
 import { api, type ImportResult, type ImportBackupResult } from "../lib/api";
 import { eventBus } from "../lib/eventBus";
 import type { WSMessage, ImportProgressMessage } from "../lib/types";
+import { PathPickButton } from "./PathPickButton";
 
 type Mode = "rescan" | "path" | "upload" | "backup";
 
@@ -426,14 +427,17 @@ export function ImportHistory() {
           {mode === "path" && (
             <div className="space-y-3">
               <div>
-                <input
-                  type="text"
-                  value={folderPath}
-                  onChange={(e) => setFolderPath(e.target.value)}
-                  placeholder={t("import.folderPlaceholder")}
-                  className="input w-full text-sm font-mono"
-                  spellCheck={false}
-                />
+                <div className="flex gap-1.5">
+                  <input
+                    type="text"
+                    value={folderPath}
+                    onChange={(e) => setFolderPath(e.target.value)}
+                    placeholder={t("import.folderPlaceholder")}
+                    className="input w-full text-sm font-mono"
+                    spellCheck={false}
+                  />
+                  <PathPickButton start={folderPath} onPick={setFolderPath} />
+                </div>
                 <p className="text-[11px] text-fg-muted mt-1.5">{t("import.folderHelper")}</p>
               </div>
               <div className="flex justify-end">