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/lanes/startSession.ts

@@ -1,14 +1,15 @@
 /**
  * @file startSession.ts — starting a session in a workspace's first free tab
  * (`POST /api/lanes/:id/start` with `slot: "auto"`) and the small pane-slot
- * helpers around it. Kept out of `WorkspaceHome.tsx` so the sidebar's row menu
- * can start a session without pulling the whole home (and react-markdown) into
+ * helpers around it. Kept out of `WorkspaceHome.tsx` so the sidebar's session
+ * list can use them without pulling the whole home (and react-markdown) into
  * the main bundle.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 
 import i18n from "../../i18n";
 import { api, type RunHandle } from "../../lib/api";
+import { MAX_SLOTS } from "../../lib/paneLayout";
 
 /** The tmux session a pane slot of a lane owns (server/lib/pty-run.js). */
 export function paneRunId(laneId: number, slot: number): string {
@@ -31,7 +32,7 @@ export async function startInFreeTab(
 
 /** The workspace a pane belongs to, from its tmux name `agenthub-lane-<id>[-slot]`. */
 export function laneOfRun(runId: string): number | null {
-  const m = /^agenthub-lane-(\d+)(?:-[1-3])?$/.exec(runId);
+  const m = /^agenthub-lane-(\d+)(?:-[1-9])?$/.exec(runId);
   return m ? Number(m[1]) : null;
 }
 
@@ -54,10 +55,11 @@ export async function startInFreeTabDetailed(
   }
 }
 
-/** The first pane slot with no live run, or null when all four are busy. */
+/** The first pane slot with no live run, or null when all ten are busy. */
 export function freeSlot(laneId: number, runs: RunHandle[]): number | null {
   const busy = new Set(
     runs.filter((r) => r.laneId === laneId && r.status === "running").map((r) => r.slot ?? 0)
   );
-  return [0, 1, 2, 3].find((s) => !busy.has(s)) ?? null;
+  for (let s = 0; s < MAX_SLOTS; s++) if (!busy.has(s)) return s;
+  return null;
 }