Replace mock Agent Shell overlay with inline xterm PTY and dock/expand UX.

Uses a local-operator WebSocket bash session, keeps the map interactive, and SNAP docks the shell back into Mesh Chat instead of a floating blurred panel.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_agent_shell_settings.py

@@ -0,0 +1,14 @@
+def test_agent_shell_settings_roundtrip(tmp_path, monkeypatch):
+    from services import agent_shell_settings
+
+    settings_path = tmp_path / "agent_shell_settings.json"
+    workdir = tmp_path / "workspace"
+    workdir.mkdir()
+
+    monkeypatch.setattr(agent_shell_settings, "_SETTINGS_FILE", settings_path)
+
+    assert agent_shell_settings.get_agent_shell_settings()["working_directory"]
+
+    saved = agent_shell_settings.set_agent_shell_working_directory(str(workdir))
+    assert saved["working_directory"] == str(workdir.resolve())
+    assert agent_shell_settings.get_agent_shell_settings()["working_directory"] == str(workdir.resolve())