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/communication/resolver.py

@@ -0,0 +1,32 @@
+"""
+Address resolver — resolves agent names/roles to their network addresses.
+"""
+
+from __future__ import annotations
+from typing import Dict, List, Optional
+
+
+class AddressResolver:
+    """Resolves symbolic agent names and roles to concrete agent IDs."""
+
+    def __init__(self) -> None:
+        self._name_table: Dict[str, str] = {}  # name -> agent_id
+        self._role_table: Dict[str, List[str]] = {}  # role -> [agent_ids]
+
+    def register(self, name: str, agent_id: str, role: Optional[str] = None) -> None:
+        self._name_table[name] = agent_id
+        if role:
+            self._role_table.setdefault(role, []).append(agent_id)
+
+    def resolve_by_name(self, name: str) -> Optional[str]:
+        return self._name_table.get(name)
+
+    def resolve_by_role(self, role: str) -> List[str]:
+        return self._role_table.get(role, [])
+
+    def unregister(self, name: str) -> Optional[str]:
+        agent_id = self._name_table.pop(name, None)
+        if agent_id:
+            for role, ids in self._role_table.items():
+                self._role_table[role] = [i for i in ids if i != agent_id]
+        return agent_id