perf(proxies): cache expressvpn and proton catalogues across requests

A config reload clears the cache; a failed answer is never kept.

tests/core/test_proxy_catalogue_cache.py

@@ -35,3 +35,33 @@ def test_empty_catalogue_is_not_kept() -> None:
     fetch()
     fetch()
     assert len(calls) == 2
+
+
+def test_login_bound_providers_fetch_once_across_builds(monkeypatch: pytest.MonkeyPatch, tmp_path) -> None:
+    from types import SimpleNamespace
+
+    from unshackle.core.proxies.expressvpn import ExpressVPN
+    from unshackle.core.proxies.proton import ProtonVPN
+
+    requests_made: list[str] = []
+
+    def express_request(self: ExpressVPN, method: str, url: str, **_: object) -> SimpleNamespace:
+        requests_made.append("express")
+        return SimpleNamespace(json=lambda: {"locations": [{"country_code": "ca"}]})
+
+    def proton_api(self: ProtonVPN, method: str, path: str) -> SimpleNamespace:
+        requests_made.append(path)
+        body = {"LogicalServers": [{"ExitCountry": "CA"}]} if path.endswith("logicals") else {"VPN": {"MaxTier": 0}}
+        return SimpleNamespace(json=lambda: body)
+
+    monkeypatch.setattr(ExpressVPN, "get_srt", lambda self: "srt")
+    monkeypatch.setattr(ExpressVPN, "request", express_request)
+    monkeypatch.setattr(ProtonVPN, "api", proton_api)
+
+    for _ in range(2):
+        assert ExpressVPN(cache_path=str(tmp_path / "e.json")).get_locations() == [{"country_code": "ca"}]
+        proton = ProtonVPN(cookie_path=str(tmp_path / "c.txt"), cache_path=str(tmp_path / "p.json"))
+        assert proton.get_logicals() == [{"ExitCountry": "CA"}]
+        assert proton.get_max_tier() == 0
+
+    assert sorted(requests_made) == ["/vpn", "/vpn/v1/logicals", "express"]