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>

tests/unit/test_config.py

@@ -1,4 +1,4 @@
-"""Tests for multi_swarm.config.Settings.
+"""Tests for multi_swarm_core.config.Settings.
 
 Note on .env isolation:
 The happy-path test relies on monkeypatch.setenv to provide values.
@@ -10,7 +10,7 @@ absence of required env vars. This keeps the test deterministic both in CI
 
 import pytest
 
-from multi_swarm.config import Settings
+from multi_swarm_core.config import Settings
 
 
 def test_settings_loads_from_env(monkeypatch: pytest.MonkeyPatch) -> None: