feat: implement DCOS source tree, tests, and build configuration

Complete implementation of the DCOS package including:
- 40+ Python source files across agents, communication, core, learning, memory, protocols, utils
- pyproject.toml build configuration
- 102 unit tests across all subsystems
- Fixed flake.nix (Python 3.12, proper dependencies, pyproject build)
- Fixed .woodpecker.yml (correct paths, removed silent-fail flags)
- Added .gitignore
- Cleared stale pytest cache

tests/test_protocols/test_user_interface.py

@@ -0,0 +1,27 @@
+"""
+Tests for UserInterface.
+"""
+
+import pytest
+from dcos.protocols.user_interface import UserInterface, UserRequest, SystemResponse
+
+
+class TestUserInterface:
+    def test_process_input(self):
+        ui = UserInterface()
+        request = UserRequest(input="hello", user_id="user_1")
+        parsed = ui.process_input(request)
+        assert parsed["intent"] == "query"
+
+    def test_format_response(self):
+        ui = UserInterface()
+        response = SystemResponse(output="Hello!", agent_id="agent_1")
+        formatted = ui.format_response(response)
+        assert "[agent_1]" in formatted
+
+    def test_history(self):
+        ui = UserInterface()
+        ui.format_response(SystemResponse(output="msg1", agent_id="a"))
+        ui.format_response(SystemResponse(output="msg2", agent_id="b"))
+        history = ui.get_history()
+        assert len(history) == 2