fix(spells): backfill casting times for all imported spells

data/spells/unseen_servant.json

@@ -5,6 +5,7 @@
   "range": "close",
   "save": "none",
   "base_dc": 10,
+  "cast_time": "standard",
   "effects": [],
   "description": "An invisible, mindless, shapeless force performs simple tasks at your command for 1 hour/level: fetching, opening unstuck doors, holding chairs, cleaning or mending (effective Strength 2, speed 15 ft., no attacks, DC 10 skill limit). No combat effect: object manipulation by invisible servants is not modeled by the engine."
 }