Add ClassicAPI dispel-type conditionals via C_UnitAuras

Introduce ClassicAPI.lua, a feature-detection layer for the ClassicAPI
client mod that mirrors NampowerAPI's HasMinimumVersion pattern
(IsAvailable / HasMinimumVersion / HasUnitAuras). UnitHasDispelType
scans a unit's auras via C_UnitAuras and reports the dispel type,
scanning debuffs or buffs based on a helpful flag.

Add conditionals backed by it:
- Debuff side (defensive cleanse): [magic] [curse] [disease] [poison]
  [dispellable] + negations
- Buff side (offensive dispel/strip): [magicbuff] [dispellablebuff]
  + negations

All are no-arg booleans, default to @target (honor @unit), and degrade
gracefully without ClassicAPI: positive checks return false, negated
return true, since vanilla cannot read aura dispel types. The existing
ValidateAura path is untouched. MacroErrorChecker auto-accepts them via
the Keywords table; they're registered in BOOLEAN_CONDITIONALS so they
parse as flags. Loaded after NampowerAPI in the TOC.

Core.lua

@@ -152,6 +152,21 @@ local BOOLEAN_CONDITIONALS = {
     nopet = true,
     bg = true,
     nobg = true,
+    -- Dispel-type conditionals (ClassicAPI C_UnitAuras)
+    magic = true,
+    nomagic = true,
+    curse = true,
+    nocurse = true,
+    disease = true,
+    nodisease = true,
+    poison = true,
+    nopoison = true,
+    dispellable = true,
+    nodispellable = true,
+    magicbuff = true,
+    nomagicbuff = true,
+    dispellablebuff = true,
+    nodispellablebuff = true,
 }
 
 local requirementCheckFrame = CreateFrame("Frame")