MidnightNameplates 0.8.0 - Phase 8: Classification System

Added:
- Classification detection for Normal, Elite, Rare, Rare Elite, Boss and Quest/Important units.
- Per-classification scale multiplier.
- Per-classification alpha multiplier.
- Per-classification name color.
- Per-classification frame color when Frame Mode = MIDNIGHT.
- Optional Midnight-native text/dot/short classification indicator.
- Indicator placement support (runtime-ready).
- WoW 12.1 secret-value guards around UnitClassification and quest-boss checks.
- Existing Phase 7 unit-type settings remain intact.

Test:
1. Normal enemy NPCs.
2. Elite mobs.
3. Rare and rare elite mobs if available.
4. Boss/worldboss units.
5. Quest boss / quest-important mobs.
6. Verify Unit Types still work.
7. Verify target, threat, auras, casts, and execute warning still work.
8. Watch for Lua, taint, or protected-action errors.
