fix(CORE-001D3A): accept decimal boundary inputs

app/services/boundary_values.py

@@ -0,0 +1,25 @@
+from __future__ import annotations
+
+from decimal import Decimal, InvalidOperation
+
+from app.domain.units import decimal_from_float, to_decimal
+
+
+def boundary_decimal(value: object, *, field_name: str) -> Decimal:
+    if value is None:
+        raise ValueError(f"{field_name} must be present")
+    if isinstance(value, bool):
+        raise TypeError(f"{field_name} must be numeric, got bool")
+    if isinstance(value, float):
+        return decimal_from_float(value)
+    if isinstance(value, (Decimal, int)):
+        return to_decimal(value)
+    if isinstance(value, str):
+        stripped = value.strip()
+        if not stripped:
+            raise ValueError(f"{field_name} must be present")
+        try:
+            return to_decimal(stripped)
+        except InvalidOperation as exc:
+            raise ValueError(f"{field_name} must be numeric, got {value!r}") from exc
+    raise TypeError(f"{field_name} must be numeric, got {type(value)!r}")