feat(api): esponi API library pubblica via __all__ in protocol/backtest/cerbero/data

Cristallizza la library surface che il nuovo repo figlio
Swarm_Strategy_Crypto consumerà via git submodule:
- multi_swarm.protocol.{compile,parse,validate}_strategy + AST nodes
- multi_swarm.backtest.{Side, Trade, Order, Position, BacktestEngine}
- multi_swarm.cerbero.CerberoClient
- multi_swarm.data.{CerberoOHLCVLoader, OHLCVRequest}

Cambi a queste signature dovranno essere considerati breaking
per il consumer downstream.

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

src/multi_swarm/backtest/__init__.py

@@ -0,0 +1,13 @@
+"""Backtest layer: order/position/trade dataclasses + engine."""
+
+from .engine import BacktestEngine, BacktestResult
+from .orders import Order, Position, Side, Trade
+
+__all__ = [
+    "BacktestEngine",
+    "BacktestResult",
+    "Order",
+    "Position",
+    "Side",
+    "Trade",
+]

src/multi_swarm/cerbero/__init__.py

@@ -0,0 +1,5 @@
+"""Cerbero data-provider HTTP client."""
+
+from .client import CerberoClient
+
+__all__ = ["CerberoClient"]

src/multi_swarm/data/__init__.py

@@ -0,0 +1,5 @@
+"""Data loaders: OHLCV via Cerbero, train/test splits."""
+
+from .cerbero_ohlcv import CerberoOHLCVLoader, OHLCVRequest
+
+__all__ = ["CerberoOHLCVLoader", "OHLCVRequest"]