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

data/spells/prestidigitation.json

@@ -5,6 +5,7 @@
   "range": "close",
   "save": "none",
   "base_dc": 10,
+  "cast_time": "standard",
   "effects": [],
   "description": "A cantrip: minor magical tricks for 1 hour - lift 1 lb. of material, color/clean/soil items in a 1-ft cube, chill/warm/flavor 1 lb. of nonliving material, or create crude trinkets. It can deal no damage and duplicates no other spell. No combat effect; the trivial manipulations are not modeled by the engine."
 }