feat(combat): expose weapon reference in observation snapshot

src/pf1e_simulator/dice.py

@@ -122,3 +122,20 @@ def parse_dice(text: str) -> DiceExpr:
         raise DiceParseError(text) from None
 
     return DiceExpr.flat(n)
+
+
+def dice_to_str(expr: DiceExpr) -> str:
+    """Serialize a DiceExpr into canonical dice notation.
+
+    Inverse of `parse_dice`: flat expressions (count=0) render as the bare
+    integer, dice expressions render as "NdS" with a signed bonus appended
+    only when non-zero.
+    """
+    if expr.count == 0:
+        return str(expr.bonus)
+    base = f"{expr.count}d{expr.sides}"
+    if expr.bonus > 0:
+        return f"{base}+{expr.bonus}"
+    if expr.bonus < 0:
+        return f"{base}{expr.bonus}"
+    return base