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_memory/test_episodic.py

@@ -0,0 +1,33 @@
+"""
+Tests for EpisodicMemory.
+"""
+
+import pytest
+from dcos.memory.episodic import EpisodicMemory
+
+
+class TestEpisodicMemory:
+    def test_record_and_recall(self):
+        mem = EpisodicMemory()
+        ep = mem.record({"action": "test"}, "success", "test episode")
+        assert ep.summary == "test episode"
+
+    def test_recall_recent(self):
+        mem = EpisodicMemory()
+        for i in range(5):
+            mem.record({"i": i}, f"outcome_{i}")
+        recent = mem.recall_recent(3)
+        assert len(recent) == 3
+
+    def test_search_by_context(self):
+        mem = EpisodicMemory()
+        mem.record({"type": "exploration"}, "found gold")
+        mem.record({"type": "exploitation"}, "mined ore")
+        results = mem.search_by_context("type", "exploration")
+        assert len(results) == 1
+
+    def test_count(self):
+        mem = EpisodicMemory()
+        assert mem.episode_count() == 0
+        mem.record({}, "outcome")
+        assert mem.episode_count() == 1