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_agents/test_domain.py

@@ -0,0 +1,22 @@
+"""
+Tests for DomainExpertAgent.
+"""
+
+import pytest
+from dcos.agents.domain import DomainExpertAgent
+
+
+class TestDomainExpertAgent:
+    def test_domain_initialization(self):
+        agent = DomainExpertAgent(name="medical", domain="medicine")
+        assert agent.domain == "medicine"
+
+    def test_answer_question(self):
+        agent = DomainExpertAgent(domain="physics")
+        answer = agent.answer("What is gravity?")
+        assert "[physics]" in answer
+
+    def test_act(self):
+        agent = DomainExpertAgent(domain="chemistry")
+        result = agent.act({"question": "What is water?"})
+        assert result["domain"] == "chemistry"