fix(tui): correct --skip-build hint and add TUI workspace install test

- Update the --skip-build pre-build hint in the dashboard startup path
  to use `npm install --workspace web && npm run build -w web` so users
  don't accidentally trigger a desktop rebuild by following the hint.

- Add test_tui_launch_install_uses_workspace_scope to assert that the
  TUI launch npm install carries --workspace ui-tui, covering the call
  site added in the prior commit.

hermes_cli/main.py

@@ -12412,7 +12412,7 @@ def cmd_dashboard(args):
         )
         if not (_dist_root / "index.html").exists():
             print(f"✗ --skip-build was passed but no web dist found at: {_dist_root}")
-            print("  Pre-build first:  cd web && npm install && npm run build")
+            print("  Pre-build first:  npm install --workspace web && npm run build -w web")
             print("  Or drop --skip-build to build automatically.")
             sys.exit(1)
         print(f"→ Skipping web UI build (--skip-build); using dist at {_dist_root}")

tests/hermes_cli/test_tui_npm_install.py

@@ -390,3 +390,36 @@ def test_no_stray_lockfiles_in_workspace_subdirs(main_mod) -> None:
         "delete them and run `npm install` from the repo root instead: "
         + ", ".join(str(d / "package-lock.json") for d in stray)
     )
+
+
+def test_tui_launch_install_uses_workspace_scope(
+    tmp_path: Path, main_mod, monkeypatch
+) -> None:
+    """TUI launch npm install must pass --workspace ui-tui to avoid pulling apps/desktop."""
+    tui_dir = tmp_path / "ui-tui"
+    tui_dir.mkdir()
+    (tui_dir / "package.json").write_text("{}")
+    (tui_dir / "dist" / "entry.js").parent.mkdir(parents=True)
+    (tui_dir / "dist" / "entry.js").write_text("console.log('tui')")
+    # workspace root: parent has lockfile, tui_dir does not
+    (tmp_path / "package-lock.json").write_text("{}")
+
+    monkeypatch.setattr(main_mod, "_tui_need_npm_install", lambda _root: True)
+    monkeypatch.setattr(main_mod, "_tui_need_rebuild", lambda _root: False)
+    monkeypatch.setattr(main_mod.shutil, "which", lambda name: f"/usr/bin/{name}")
+
+    npm_calls = []
+
+    def fake_run(cmd, **kwargs):
+        if cmd[0].endswith("npm"):
+            npm_calls.append(cmd)
+        return types.SimpleNamespace(returncode=0, stdout="", stderr="")
+
+    monkeypatch.setattr(main_mod.subprocess, "run", fake_run)
+
+    main_mod._make_tui_argv(tui_dir, tui_dev=False)
+
+    assert npm_calls, "expected npm install to be called"
+    install_cmd = npm_calls[0]
+    assert "--workspace" in install_cmd
+    assert "ui-tui" in install_cmd