fix(desktop): resolve electronDist to the actual electron install location (#48081)

After the June lockfile regeneration (#46652) floated electron and reshuffled
npm workspace hoisting, the desktop pack fails with "The specified electronDist
does not exist". apps/desktop/package.json pointed electronDist at the repo
root (../../node_modules/electron/dist) while npm now installs electron nested
under apps/desktop/node_modules/electron. The two contradict, so a clean
install can never package the app (Windows + macOS).

- electronDist -> node_modules/electron/dist (resolved relative to apps/desktop,
  i.e. the workspace-local install npm actually produces).
- hermes_cli/main.py, scripts/install.sh, scripts/install.ps1: add a runtime
  electron-dir resolver that prefers apps/desktop/node_modules/electron and
  falls back to the root hoist, so dist checks + the mirror re-download work
  under either npm layout.
- patch-electron-builder-mac-binary.cjs: try the workspace-local Electron.app
  before the root hoist in the macOS binary-restore fallback (sibling site no
  PR touched).
- test: assert build.electronDist resolves to where the lockfile installs
  electron, so a future hoist change (root <-> nested) can't silently break it.

Salvages the overlapping work in #48003 (sitkarev), #48012 (omegazheng), and
#48033 (james47kjv).

Co-authored-by: sitkarev <59806492+sitkarev@users.noreply.github.com>
Co-authored-by: omegazheng <zheng@omegasys.eu>
Co-authored-by: james47kjv <220877172+james47kjv@users.noreply.github.com>

tests/hermes_cli/test_gui_command.py

@@ -616,6 +616,33 @@ def test_electron_dist_ok_per_platform(tmp_path, monkeypatch, platform, rel):
     assert cli_main._electron_dist_ok(tmp_path) is True
 
 
+def test_electron_dir_prefers_workspace_local_package(tmp_path):
+    """npm may nest electron under apps/desktop; resolve there over the root hoist."""
+    root_electron = tmp_path / "node_modules" / "electron"
+    local_electron = tmp_path / "apps" / "desktop" / "node_modules" / "electron"
+    root_electron.mkdir(parents=True)
+    local_electron.mkdir(parents=True)
+
+    assert cli_main._electron_dir(tmp_path) == local_electron
+
+
+def test_electron_dir_falls_back_to_root_hoist(tmp_path):
+    """When npm hoists electron to the repo root, resolve there."""
+    root_electron = tmp_path / "node_modules" / "electron"
+    root_electron.mkdir(parents=True)
+
+    assert cli_main._electron_dir(tmp_path) == root_electron
+
+
+def test_electron_dist_ok_finds_workspace_local_binary(tmp_path, monkeypatch):
+    """A nested apps/desktop electron with a valid binary counts as ok."""
+    monkeypatch.setattr(cli_main.sys, "platform", "linux")
+    binp = tmp_path / "apps" / "desktop" / "node_modules" / "electron" / "dist" / "electron"
+    binp.parent.mkdir(parents=True)
+    binp.write_text("", encoding="utf-8")
+    assert cli_main._electron_dist_ok(tmp_path) is True
+
+
 def test_redownload_electron_dist_noop_when_present(tmp_path, monkeypatch):
     """Already-healthy dist → no download, so an unrelated build failure can't
     trigger a needless ~200 MB refetch."""

tests/test_desktop_electron_pin.py

@@ -94,3 +94,42 @@ def test_lockfile_resolves_the_pinned_electron():
         f"but the pin is {spec!r}; run `npm install --package-lock-only` so "
         "`npm ci` stays consistent."
     )
+
+
+def test_electron_dist_matches_lockfile_install_location():
+    """build.electronDist must point at where the lockfile installs Electron.
+
+    electron-builder copies the unpacked Electron from ``build.electronDist``
+    (resolved relative to ``apps/desktop``). npm workspace hoisting is not
+    deterministic across machines/npm versions: it may nest Electron under
+    ``apps/desktop/node_modules/electron`` or hoist it to the repo root. If
+    electronDist points at one location while the lockfile installs at the
+    other, packaging fails with ``The specified electronDist does not exist`` —
+    the "Building desktop app" failure reported after the June lockfile
+    regeneration floated Electron and reshuffled the hoist. Lock the two
+    together so a hoist change (root <-> nested) can't silently break the path
+    again.
+    """
+    if not ROOT_LOCK.is_file():
+        pytest.skip("root package-lock.json not present")
+    electron_dist = _desktop_pkg().get("build", {}).get("electronDist")
+    assert electron_dist, "build.electronDist is missing"
+
+    lock = json.loads(ROOT_LOCK.read_text(encoding="utf-8"))
+    electron_paths = [
+        path
+        for path in lock.get("packages", {})
+        if path.endswith("node_modules/electron")
+    ]
+    assert electron_paths, "no electron entry found in package-lock.json"
+
+    desktop_dir = REPO_ROOT / "apps" / "desktop"
+    # electronDist is resolved relative to the apps/desktop project dir.
+    configured = (desktop_dir / electron_dist).resolve()
+    # Where the lockfile actually places Electron's unpacked dist.
+    installed = {(REPO_ROOT / p / "dist").resolve() for p in electron_paths}
+    assert configured in installed, (
+        f"build.electronDist={electron_dist!r} resolves to {configured}, but the "
+        f"lockfile installs Electron at {sorted(str(p) for p in installed)}. "
+        "electron-builder will fail with 'electronDist does not exist'."
+    )