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

.woodpecker.yml

@@ -5,9 +5,9 @@ steps:
   - name: lint-and-test
     image: python:3.12-slim
     commands:
-      - pip install --break-system-packages ruff pytest asyncpg redis aiosqlite pyyaml
+      - pip install --break-system-packages ruff pytest asyncpg redis aiosqlite pyyaml pydantic
       - ruff check src/dcos/
-      - pytest tests/test_memory/ tests/test_core/ -x --tb=short -q || true
+      - PYTHONPATH=src:$PYTHONPATH pytest tests/ -x --tb=short -q
     when:
       event: push