fix(rules): condition durations scale with caster level (hold person, doom, touch of fatigue, vanish)

ConditionEffect gains duration_rounds_per_level and max_duration_rounds
(mirroring PenaltyEffect), applied as caster_level * per_level rounds capped
at max: hold person 1 rd/lvl, doom 1 min/lvl, touch of fatigue 1 rd/lvl,
vanish 1 rd/lvl (max 5). Extend Spell doubles both the per-level rate and
the cap. Tests cover scaling and the vanish cap.

data/spells/vanish.json

@@ -10,7 +10,9 @@
     {
       "type": "condition",
       "condition_name": "invisible",
-      "duration_rounds": 5,
+      "duration_rounds": 1,
+      "duration_rounds_per_level": 1,
+      "max_duration_rounds": 5,
       "save_negates": false
     }
   ],