feat(fase1): export domain-model public API + green full suite (F1)

tests/test_imports_core.py

@@ -21,3 +21,25 @@ def test_core_runtime_deps_importable_and_cbc_available() -> None:
         # PuLP 3.3.2's available() returns the resolved CBC binary PATH (a truthy str) when
         # present, not the bool True — so assert truthiness, not identity.
         assert pulp.PULP_CBC_CMD(msg=False).available()
+
+
+def test_fase1_domain_model_public_api_importable() -> None:
+    """SC10: every Fase 1 domain-model symbol is importable from the package root (the explicit
+    __all__ export), so a deployer reaches the new API without deep-importing submodules."""
+    import portfolio_optimiser as po
+
+    expected = {
+        "Dimension",
+        "admits",
+        "SavingsLedger",
+        "LedgerEntry",
+        "realize",
+        "RealizationRefused",
+        "GoalContract",
+        "GoalConfig",
+        "load_goal_config",
+        "GoalReached",
+    }
+    assert expected <= set(po.__all__)  # each is publicly exported
+    for name in expected:
+        assert hasattr(po, name), f"{name} is in __all__ but not importable from the package root"