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

src/dcos/memory/__init__.py

@@ -0,0 +1,25 @@
+"""
+Memory subsystem — multiple memory types and the unified facade.
+"""
+
+from .working import WorkingMemory
+from .conversation import ConversationMemory
+from .long_term import LongTermMemory
+from .semantic import SemanticMemory
+from .episodic import EpisodicMemory
+from .procedural import ProceduralMemory
+from .user_model import UserModel
+from .world_model import WorldModel
+from .memory_facade import MemoryFacade
+
+__all__ = [
+    "WorkingMemory",
+    "ConversationMemory",
+    "LongTermMemory",
+    "SemanticMemory",
+    "EpisodicMemory",
+    "ProceduralMemory",
+    "UserModel",
+    "WorldModel",
+    "MemoryFacade",
+]