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

data/spells/mending.json

@@ -5,6 +5,7 @@
   "range": "close",
   "save": "will",
   "base_dc": 10,
+  "cast_time": "long",
   "effects": [],
   "description": "A cantrip: after 10 minutes, the spell repairs 1d4 hit points of damage to one object (up to 1 lb./level), removing the broken condition if restored to at least half HP. Will negates (harmless, object). Object repair is outside the engine's combat model, so the spell has no mechanical effects here."
 }