feat(observation): expose structured spell areas

src/pf1e_simulator/combat.py

@@ -268,6 +268,19 @@ def _spell_half_on_save(spell: SpellSpec) -> bool:
     return False
 
 
+def _spell_area_dict(spell: SpellSpec) -> dict[str, object] | None:
+    """Structured area template of a spell, or None if it has no top-level AreaEffect.
+
+    Returns ``{"shape": str, "radius_ft": int}`` for the FIRST AreaEffect found
+    in ``spell.effects`` (a spell may declare several effects; only the first
+    area is exposed, and effects nested inside an AreaEffect are not scanned).
+    """
+    for effect in spell.effects:
+        if isinstance(effect, AreaEffect):
+            return {"shape": effect.shape, "radius_ft": effect.radius_ft}
+    return None
+
+
 _STEP_DELTAS: tuple[Pos, ...] = (
     (-1, -1),
     (-1, 0),
@@ -3710,6 +3723,7 @@ class CombatEngine:
                 "summary": "",
                 "half_on_save": False,
                 "save_negates": False,
+                "area": None,
             }
         half_on_save = _spell_half_on_save(spell)
         return {
@@ -3722,6 +3736,7 @@ class CombatEngine:
             "summary": _spell_summary(spell),
             "half_on_save": half_on_save,
             "save_negates": spell.save != "none" and not half_on_save,
+            "area": _spell_area_dict(spell),
         }
 
     def _cast_spell(