fix(gui): clarifier aide et disponibilite moteurs

Passe theme clair, libelles utilisateur, aides conteneurs, recherche de mise a jour et indication honnete des moteurs optionnels non embarques. Tests GUI unitaires: 126 passed.

tests/unit/test_gui_v6_license_client.py

@@ -28,9 +28,11 @@ class FakeResponse:
 class FakeSession:
     """Session HTTP mockable : enregistre les appels, renvoie des réponses scriptées."""
 
-    def __init__(self, response=None, exc=None):
+    def __init__(self, response=None, exc=None, get_response=None, get_exc=None):
         self._response = response
         self._exc = exc
+        self._get_response = response if get_response is None else get_response
+        self._get_exc = exc if get_exc is None else get_exc
         self.calls = []
 
     def post(self, url, json, timeout):
@@ -39,6 +41,12 @@ class FakeSession:
             raise self._exc
         return self._response
 
+    def get(self, url, timeout):
+        self.calls.append({"url": url, "timeout": timeout})
+        if self._get_exc is not None:
+            raise self._get_exc
+        return self._get_response
+
 
 def _client(tmp_path, session):
     store = LicenseStore(tmp_path / "license.json")
@@ -173,6 +181,29 @@ def test_local_status_reads_store(tmp_path):
     assert status.license_ref == "LIC-7"
 
 
+def test_latest_version_reads_active_artifact(tmp_path):
+    payload = {
+        "version": "v11.0-beta",
+        "channel": "beta",
+        "filename": "Anonymisation-Setup.exe",
+    }
+    session = FakeSession(get_response=FakeResponse(200, payload))
+    client, _ = _client(tmp_path, session)
+
+    version = client.latest_version()
+
+    assert version == payload
+    assert session.calls[0]["url"] == "https://portail.example/api/v1/version"
+
+
+def test_latest_version_unavailable_on_404_or_network_error(tmp_path):
+    client_404, _ = _client(tmp_path, FakeSession(get_response=FakeResponse(404, {"detail": "No active version"})))
+    assert client_404.latest_version() is None
+
+    client_down, _ = _client(tmp_path, FakeSession(get_exc=TimeoutError("timeout")))
+    assert client_down.latest_version() is None
+
+
 def test_status_never_exposes_token():
     # Le statut ne porte pas de token : la repr ne peut pas le fuiter.
     status = LicenseStatus.from_payload({"status": "active", "license_ref": "LIC-1"})