refactor(layout): rename multi_swarm → multi_swarm_core con doppia nidificazione uv workspace

- mv src/multi_swarm → src/multi_swarm_core/multi_swarm_core (member layout)
- sed-replace globale degli import: from/import multi_swarm.* → multi_swarm_core.*
- 115 occorrenze aggiornate in src/ scripts/ tests/
- multi_swarm_coevolutive (nome repo) preservato dal word boundary

Pre-condizione per il setup uv workspace della Fase 3.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.omc/state/subagent-tracking.json

@@ -0,0 +1,35 @@
+{
+  "agents": [
+    {
+      "agent_id": "aa06dbecb11544c5e",
+      "agent_type": "Explore",
+      "started_at": "2026-05-15T17:02:02.737Z",
+      "parent_mode": "none",
+      "status": "completed",
+      "completed_at": "2026-05-15T17:03:37.282Z",
+      "duration_ms": 94545
+    },
+    {
+      "agent_id": "a62f5bee30bd7a6c1",
+      "agent_type": "Explore",
+      "started_at": "2026-05-15T17:02:13.687Z",
+      "parent_mode": "none",
+      "status": "completed",
+      "completed_at": "2026-05-15T17:02:35.066Z",
+      "duration_ms": 21379
+    },
+    {
+      "agent_id": "a086f61a1fbb580be",
+      "agent_type": "Plan",
+      "started_at": "2026-05-15T17:09:00.043Z",
+      "parent_mode": "none",
+      "status": "completed",
+      "completed_at": "2026-05-15T17:12:22.595Z",
+      "duration_ms": 202552
+    }
+  ],
+  "total_spawned": 3,
+  "total_completed": 3,
+  "total_failed": 0,
+  "last_updated": "2026-05-15T17:12:22.696Z"
+}