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_communication/test_router.py

@@ -0,0 +1,32 @@
+"""
+Tests for MessageRouter.
+"""
+
+import pytest
+from dcos.communication.router import MessageRouter
+from dcos.communication.protocol import Message
+
+
+class TestMessageRouter:
+    def test_register_and_route(self):
+        router = MessageRouter()
+        router.register("weather", "agent_weather")
+        msg = Message(sender="user", recipient="", payload="weather forecast")
+        target = router.route(msg)
+        assert target == "agent_weather"
+
+    def test_fallback(self):
+        router = MessageRouter()
+        router.set_fallback("default_agent")
+        msg = Message(sender="user", recipient="", payload="unknown topic")
+        target = router.route(msg)
+        assert target == "default_agent"
+
+    def test_unregister(self):
+        router = MessageRouter()
+        router.register("key", "agent")
+        removed = router.unregister("key")
+        assert removed == "agent"
+        msg = Message(sender="user", recipient="", payload="key data")
+        target = router.route(msg)
+        assert target is None