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.
