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/components/__tests__/Sidebar.test.tsx

@@ -95,6 +95,8 @@ describe("Sidebar", () => {
     expect(hrefs).toContain("/sessions");
     expect(hrefs).toContain("/settings");
     expect(hrefs).not.toContain("/activity");
+    // The file manager serves a shared server; a local dashboard has none.
+    expect(hrefs).not.toContain("/files");
   });
 
   describe("update status line, in the connection details modal", () => {