Replace the hardcoded knownTrackingSpells class table and the
icon-substring spellbook scan with ClassicAPI's native tracking
functions:
- RefreshSpells now enumerates GetNumTrackingTypes() / GetTrackingInfo(),
which the DLL derives from the spellbook by tracking-aura effect. This
drops the per-class spell/icon table and picks up server-custom
trackers (e.g. Turtle's Find Trees) automatically.
- Selecting a tracker in the menu uses SetTracking(index) instead of
CastSpell(slot, BOOKTYPE_SPELL).
- Keep the Druid Cat Form gate on Track Humanoids (5225) and the
existing invalidSpells filter. Falls back to no entries if the tracking
API is absent.
Active icon (GetTrackingTexture), cancel (CancelTrackingBuff), and the
hover tooltip (GameTooltip:SetTrackingSpell) were already native and are
unchanged.