fix(models): reject combatant ids that misparse the transcript format

src/pf1e_simulator/models.py

@@ -410,6 +410,20 @@ class Combatant(_FrozenModel):
             raise ValueError(msg)
         return value
 
+    @field_validator("id")
+    @classmethod
+    def _validate_id(cls, value: str) -> str:
+        # The transcript line format is "round N <id>: <message>"; an id
+        # containing ": " would be mis-split by cli._parse_transcript_line,
+        # and leading/trailing whitespace breaks the "id: " join.
+        if not value or value != value.strip():
+            msg = f"combatant id must be non-empty without surrounding whitespace, got {value!r}"
+            raise ValueError(msg)
+        if ": " in value:
+            msg = f"combatant id must not contain ': ' (breaks transcript parsing), got {value!r}"
+            raise ValueError(msg)
+        return value
+
     @property
     def is_lawful(self) -> bool:
         """Law axis: LG/LN/LE."""