Comprovació d'updates a l'inici opcional + timeouts de xarxa configurables

- Opció marcable «Comprova actualitzacions a l'inici» al menú; persisteix a
  settings.json i llança la comprovació diferida en obrir la finestra.
- Tolerància a repos offline/inalcanzables: low-speed abort + techo dur de
  temps a les operacions git de xarxa (fetch/clone), evitant cuelgues.
- Timeouts exposats a settings.json (git_fetch_timeout, git_clone_timeout,
  http_timeout, git_stall_limit, git_stall_time) via NetConfig, propagats
  UI -> workers -> gitops.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

jlauncher/workers.py

@@ -25,17 +25,28 @@ class _Signals(QObject):
 class DownloadWorker(QRunnable):
     """Clona o actualiza (forzado) y refresca la metadata de un juego."""
 
-    def __init__(self, root: Path, game: Game, token: str = "") -> None:
+    def __init__(
+        self,
+        root: Path,
+        game: Game,
+        token: str = "",
+        net: gitops.NetConfig = gitops.DEFAULT_NET,
+    ) -> None:
         super().__init__()
         self.root = root
         self.game = game
         self.token = token
+        self.net = net
         self.signals = _Signals()
 
     def run(self) -> None:  # noqa: D401 - API de QRunnable
         try:
             meta: GameMeta = gitops.download(
-                self.root, self.game, log=self.signals.log.emit, token=self.token
+                self.root,
+                self.game,
+                log=self.signals.log.emit,
+                token=self.token,
+                net=self.net,
             )
         except Exception as exc:  # noqa: BLE001 - reportar a la UI
             self.signals.error.emit(str(exc))
@@ -67,11 +78,18 @@ class CheckUpdatesWorker(QRunnable):
     Emite `result(game_id, has_update)` por cada juego instalado y `finished` al final.
     """
 
-    def __init__(self, root: Path, games: list[Game], token: str = "") -> None:
+    def __init__(
+        self,
+        root: Path,
+        games: list[Game],
+        token: str = "",
+        net: gitops.NetConfig = gitops.DEFAULT_NET,
+    ) -> None:
         super().__init__()
         self.root = root
         self.games = games
         self.token = token
+        self.net = net
         self.signals = _Signals()
 
     def run(self) -> None:  # noqa: D401 - API de QRunnable
@@ -81,7 +99,11 @@ class CheckUpdatesWorker(QRunnable):
                     continue
                 try:
                     has_update = gitops.check_update(
-                        self.root, game, log=self.signals.log.emit, token=self.token
+                        self.root,
+                        game,
+                        log=self.signals.log.emit,
+                        token=self.token,
+                        net=self.net,
                     )
                 except Exception as exc:  # noqa: BLE001 - no abortar el resto
                     self.signals.log.emit(f"check {game.id}: {exc}")