feat: v2.7.8 — Artifacts hub, clone related repos as extra folders, quieter resume prompt

- Artifacts (/artifacts): claude.ai pages sessions publish (captured from the
  Artifact tool's hook), pinned workspace files, skills and plugins, each
  kept as a snapshot; shared ones appear in a Hub and a skill or plugin
  installs into the viewer's own account (server/lib/artifacts.js,
  /api/artifacts, docs/plans/artifacts/).
- Workspace extra folders: clone one or more related repos beside the
  workspace and add them in one step (POST /api/lanes/:id/sources/clone).
- A pane that ended by itself while tmux kept running is no longer offered
  for resume (tmux.serverStartedAt in reconcileOrphans).
- Changes panel: a folder that is not a git repo opens on Files, and its
  files open from there.
- Plus the parallel sessions' work in this tree: File Explorer button in the
  panel header, user delete, RSA SSH keys, chat/terminal and pet fixes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

client/src/pages/__tests__/Workspace.changesPanel.test.tsx

@@ -56,6 +56,12 @@ const { HOME, LANE_A, LANE_B } = vi.hoisted(() => {
 
 // The workspace's home (its own suite) fetches sources and memory; these
 // tests are about the session view it hides, so it is a stub here.
+// Local mode unless a test says otherwise.
+const perms = vi.hoisted(() => ({ local: true }));
+vi.mock("../../components/AuthGate", async (importOriginal) => {
+  const m = await importOriginal<typeof import("../../components/AuthGate")>();
+  return { ...m, usePermissions: () => ({ ...m.usePermissions(), local: perms.local }) };
+});
 vi.mock("../../components/lanes/WorkspaceHome", () => ({
   WorkspaceHome: () => <div data-testid="workspace-home" />,
   paneRunId: (id: number, slot: number) =>
@@ -108,6 +114,12 @@ vi.mock("../../lib/api", async (importOriginal) => {
         features: { list: r({ features: [] }), show: r({ feature: null }) },
         proof: { list: r({ features: [] }), imageUrl: () => "" },
       },
+      // The File Explorer opened from the panel header.
+      files: {
+        homes: r({ homes: [] }),
+        list: r({ path: "", parent: null, entries: [], truncated: false }),
+        trash: r({ items: [] }),
+      },
       aiProxies: { list: r({ items: [] }) },
       sessions: { list: r({ sessions: [], total: 0, limit: 50, offset: 0 }) },
     },
@@ -147,6 +159,7 @@ async function settle() {
 }
 
 beforeEach(() => {
+  perms.local = true;
   i18n.changeLanguage("en");
 });
 
@@ -203,6 +216,22 @@ describe("Workspace — the Changes panel's width", () => {
     expect(card().className).toContain("w-[25%]");
   });
 
+  it("opens the File Explorer from the button beside Full screen", async () => {
+    perms.local = false;
+    await openPanel();
+    const btn = screen.getByTestId("panel-file-explorer");
+    // Right before the window controls, in the same header strip.
+    expect(btn.nextElementSibling).toBe(screen.getByTestId("lane-changes-resize"));
+    fireEvent.click(btn);
+    expect(await screen.findByTestId("file-explorer")).toBeInTheDocument();
+  });
+
+  it("has no File Explorer button in local mode", async () => {
+    await openPanel();
+    expect(screen.queryByTestId("panel-file-explorer")).toBeNull();
+    expect(screen.getByTestId("lane-changes-resize")).toBeInTheDocument();
+  });
+
   it("remembers the width across a reload, and never asks the server", async () => {
     await openPanel();
     fireEvent.click(screen.getByTestId("lane-changes-resize"));