fix(rules): convert bane to a 50-ft enemies-only burst

SRD spells/bane.md: enemies within a 50-ft burst centered on the caster
take a -1 penalty on attack rolls and a -1 penalty on saving throws
against fear effects; Will negates. The -1 penalty is approximated with
the shaken condition (-2), matching the existing Doom approximation.

- bane.json: single-target condition -> AreaEffect burst radius_ft 50,
  targets "enemies", ConditionEffect shaken 10 rounds save_negates
  (range/save kept as medium/will for the registry pin)
- combat.py: _metamagic_transform_sub now copies AreaEffect.targets so
  an Extend Spell on an area spell preserves the allies/enemies filter
- tests: TestBaneEnemiesOnly (enemy in burst debuffed, allies/caster
  unaffected, successful Will save negates)

data/spells/bane.json

@@ -8,11 +8,19 @@
   "cast_time": "standard",
   "effects": [
     {
-      "type": "condition",
-      "condition_name": "shaken",
-      "duration_rounds": 10,
-      "save_negates": true
+      "type": "area",
+      "radius_ft": 50,
+      "targets": "enemies",
+      "save_for_half": false,
+      "effects": [
+        {
+          "type": "condition",
+          "condition_name": "shaken",
+          "duration_rounds": 10,
+          "save_negates": true
+        }
+      ]
     }
   ],
-  "description": "Enemies within range take a -1 penalty on attack rolls and saving throws (approximated with the shaken condition, -2). Will negates. Concentration 1 min/level approximated as 10 rounds."
+  "description": "SRD spells/bane.md: enemies within a 50-ft burst centered on the caster take a -1 penalty on attack rolls and a -1 penalty on saving throws against fear effects; Will negates. The -1 penalty is approximated with the shaken condition (-2 on attacks and saves), matching the existing Doom approximation. Duration 1 min/level approximated as 10 rounds."
 }

src/pf1e_simulator/combat.py

@@ -6613,6 +6613,7 @@ class CombatEngine:
                     for sub in effect.effects
                 ),
                 save_for_half=effect.save_for_half,
+                targets=effect.targets,
             )
         return effect
 

tests/test_spells.py

@@ -679,6 +679,55 @@ class TestBlessAlliesOnly:
                    for b in c.active_buffs for m in b.modifiers)
 
 
+class TestBaneEnemiesOnly:
+    """Given: a caster casting Bane (SRD: 50-ft burst, enemies, Will negates)
+    When: _cast_spell is called
+    Then: enemies in the burst are debuffed, allies and caster are not."""
+
+    def _bane_engine(
+        self,
+        targets: list[Combatant],
+        enemy: CombatantState,
+        rng_queue: list[int],
+    ) -> CombatEngine:
+        caster = _make_caster()
+        c = CombatantState(combatant=caster, side="players", pos=(0, 0), hp=caster.hp_max)
+        states = [c, enemy, *targets]
+        legend = {".": TerrainType(type="floor", move_cost=1)}
+        spec = MapSpec(name="test", terrain=tuple(["." * 12] * 12), legend=legend)
+        grid = Grid.from_spec(spec)
+        return CombatEngine(
+            ScriptedRng(rng_queue), grid, states,
+            spell_registry=load_spell_registry(_SPELLS_DIR),
+        )
+
+    def test_enemy_debuffed_allies_unaffected(self) -> None:
+        ally = CombatantState(
+            combatant=_make_target("ally", hp_max=20), side="players",
+            pos=(1, 0), hp=20,
+        )
+        enemy = CombatantState(
+            combatant=_make_target("enemy", hp_max=20), side="monsters",
+            pos=(2, 0), hp=20,
+        )
+        engine = self._bane_engine([ally], enemy, [2])  # d20=2 → save fails
+        engine._cast_spell(
+            engine._states[0], enemy, "Bane",
+        )
+        assert any(c.condition.name == "shaken" for c in enemy.active_conditions)
+        assert not ally.active_conditions
+        assert not engine._states[0].active_conditions
+
+    def test_successful_save_negates(self) -> None:
+        enemy = CombatantState(
+            combatant=_make_target("enemy", hp_max=20), side="monsters",
+            pos=(2, 0), hp=20,
+        )
+        engine = self._bane_engine([], enemy, [20])  # d20=20 → save succeeds
+        engine._cast_spell(engine._states[0], enemy, "Bane")
+        assert not enemy.active_conditions
+
+
 class TestOutOfRange:
     """Given: a target beyond the spell's maximum range
     When: _cast_spell is called