fix(spells): set the correct area shapes

SRD-verified area templates: Burning Hands 15-ft cone, Color Spray 15-ft cone, Fear 30-ft cone, Flurry of Snowballs 30-ft cone, Lightning Bolt 120-ft line (all converted from single-target/burst approximations to proper AreaEffect shapes); Fireball 20-ft burst, Sound Burst 10-ft spread, Sleep 10-ft burst, Web 20-ft spread kept. Close-range spells note the 15/30-ft RAW ranges as an approximation in their descriptions. README: cone/scaling limitations moved out of the limitations list, new area-shape + caster-level scaling rules documented, areas.py added to the architecture.

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

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

data/spells/flurry_of_snowballs.json

@@ -9,7 +9,8 @@
   "effects": [
     {
       "type": "area",
-      "radius_ft": 20,
+      "shape": "cone",
+      "radius_ft": 30,
       "save_for_half": true,
       "effects": [
         {
@@ -21,5 +22,5 @@
       ]
     }
   ],
-  "description": "A flurry of snowballs hurtles at your foes: any creature in the area takes 4d6 points of cold damage. Reflex half. The RAW 30-ft cone-shaped burst is approximated as a 20-ft burst centered on the target point."
+  "description": "SRD spells/flurry-of-snowballs.md: any creature in the 30-ft. cone-shaped burst takes 4d6 points of cold damage. Reflex half. The SRD range is 30 ft. - modeled as the closest category (close)."
 }