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

data/spells/spark.json

@@ -5,6 +5,7 @@
   "range": "close",
   "save": "fort",
   "base_dc": 10,
+  "cast_time": "standard",
   "effects": [],
   "description": "A cantrip: you create a tiny spark that ignites one unattended Fine flammable object within close range, in any weather (works as flint and steel but much faster). Fortitude negates (object). No combat effect: the spell targets objects, not creatures."
 }