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/__tests__/lanes-cli.test.js

@@ -193,6 +193,24 @@ after(() => {
   }
 });
 
+describe("agenthub workspaces", () => {
+  it("is the lanes command under the UI's word", async () => {
+    const [lanes, workspaces, workspace] = await Promise.all([
+      cli(["lanes"], LANE_DIR),
+      cli(["workspaces"], LANE_DIR),
+      cli(["workspace"], LANE_DIR),
+    ]);
+    assert.equal(workspaces.status, 0, workspaces.stderr);
+    assert.match(workspaces.stdout, /CLI lane/);
+    assert.equal(workspaces.stdout, lanes.stdout);
+    assert.equal(workspace.stdout, lanes.stdout);
+    // The old name still works but says so — on stderr, never in stdout.
+    assert.match(lanes.stderr, /old name.*agenthub workspace/);
+    assert.doesNotMatch(workspaces.stderr, /old name/);
+    assert.doesNotMatch(lanes.stdout, /old name/);
+  });
+});
+
 describe("agenthub stage", () => {
   it("reports a stage for the lane owning the current directory", async () => {
     const r = await cli(["stage", "review", "--evidence", "3 findings"], LANE_DIR);
@@ -280,6 +298,17 @@ describe("agenthub stage in a directory shared by two lanes", () => {
     assert.notEqual(await stageOf(codexLane.id), "implement");
   });
 
+  it("--workspace names the lane like --lane", async () => {
+    const r = await cli(
+      ["stage", "review", "--workspace", String(codexLane.id)],
+      DUAL_DIR,
+      NO_HARNESS
+    );
+    assert.equal(r.status, 0, r.stderr);
+    assert.equal(await stageOf(codexLane.id), "review");
+    assert.notEqual(await stageOf(claudeLane.id), "review");
+  });
+
   it("fails loudly, naming both candidates, when nothing identifies the tool", async () => {
     const before = [await stageOf(claudeLane.id), await stageOf(codexLane.id)];
     const r = await cli(["stage", "done"], DUAL_DIR, NO_HARNESS);
@@ -686,7 +715,7 @@ describe("agenthub lanes node", () => {
     assert.notEqual(r.status, 0);
     assert.match(r.stdout, /\bintake\b/);
     assert.match(r.stdout, /\bdone\b/);
-    assert.match(r.stderr, /usage: agenthub lanes node/);
+    assert.match(r.stderr, /usage: agenthub workspace node/);
   });
 
   it("--print shows a slash-command node as a claude prompt, extra args appended", async () => {