Add configuration facade (cfg) with get_current_config and open_dashboard

Introduce ConfigApi, exposing Serena's configuration and session state: get_current_config and
open_dashboard (both non-editing). The corresponding tools delegate to the API via ConfigApiMixin.

As on the tool side, opening the dashboard is only offered if the dashboard is enabled and not
opened automatically; the condition is shared (_is_dashboard_openable) and applied to the API scope
via a NamedApiInclusionDefinition, the API-side counterpart of NamedToolInclusionDefinition.

test/serena/config/test_serena_config.py

@@ -268,7 +268,10 @@ class TestAgentInterface:
             fixed_toolset = {"serena_repl", "initial_instructions", "activate_project"}
             assert {t.get_name() for t in agent.get_exposed_tool_instances()} == fixed_toolset
             assert set(agent.get_active_tool_names()) == fixed_toolset
-            assert "s.mem" in agent.get_repl().entrypoint.overview()
+            overview = agent.get_repl().entrypoint.overview()
+            assert "s.mem" in overview
+            # the dashboard is disabled in the test configuration, so opening it is not offered
+            assert "s.cfg" in overview and "open_dashboard" not in overview
 
             # after activation: the toolset is unchanged, the REPL reflects the project's API exclusions
             agent.activate_project_from_path_or_name(name)

test/serena/test_cfg_api.py

@@ -0,0 +1,25 @@
+"""
+Tests for the configuration facade API.
+"""
+
+from unittest.mock import MagicMock
+
+from serena.repl.api.cfg_api import ConfigApi
+from serena.repl.facade import ApiScope, Facade
+
+
+def test_facade_exposes_config_operations() -> None:
+    facade = Facade.from_api(ConfigApi(MagicMock()), ApiScope())
+    assert facade.name == "cfg"
+    assert set(facade.enabled_method_names) == {"get_current_config", "open_dashboard"}
+    assert not any(facade.get_method(name).info.can_edit for name in facade.enabled_method_names)
+
+
+def test_operations_delegate_to_agent() -> None:
+    agent = MagicMock()
+    agent.get_current_config_overview.return_value = "overview"
+    agent.open_dashboard.return_value = False
+    agent.get_dashboard_url.return_value = "http://localhost:1"
+    api = ConfigApi(agent)
+    assert api.get_current_config() == "overview"
+    assert "http://localhost:1" in api.open_dashboard()