feat(rules): scale spell damage with caster level

DamageEffect gains optional scaling (1dX per N levels, capped) and scaling_flat (+X per N levels, capped) specs; effective_formula resolves them against the caster's level at cast time, so scaled dice flow through crits, energy resistance and metamagic like the base formula (CRB Magic - Caster Level). Loader rejects mismatched die types. Data: Fireball/Lightning Bolt 1d6/lvl max 10d6, Burning Hands 1d4/lvl max 5d4, Shocking Grasp 1d6/lvl max 5d6, Inflict Light Wounds +1/lvl max +5 (SRD-verified). Cure Light Wounds stays flat: its golden transcript pins 1d8+1 and HealEffect scaling is out of scope.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

data/spells/inflict_light_wounds.json

@@ -9,10 +9,11 @@
   "effects": [
     {
       "type": "damage",
-      "formula": "1d8+1",
+      "formula": "1d8",
       "types": ["negative"],
-      "half_on_save": true
+      "half_on_save": true,
+      "scaling_flat": { "amount": 1, "per_levels": 1, "max": 5 }
     }
   ],
-  "description": "Touching a creature channels negative energy, dealing 1d8 points of damage + 1 per caster level (maximum +5); at caster level 1 this is modeled as 1d8+1. Will half. Undead are instead cured of a like amount of damage - the engine only models the damaging side against living targets."
+  "description": "SRD spells/inflict-light-wounds.md: touching a creature channels negative energy, dealing 1d8 points of damage + 1 point per caster level (maximum +5). Will half. Undead are instead cured of a like amount of damage - the engine only models the damaging side against living targets."
 }