MidnightNameplates Phase 9.3.4 - Clean Config Restore

SOURCE OF TRUTH:
- Rebuilt directly from clean Phase 9.2 RuleManagerUsability baseline.

WHAT WAS DONE:
- No shared config helper was modified.
- Phase 9.3 advanced rule controls were re-applied only inside BuildRules().
- CreateTextButton callers use button.label only.
- Direct FontStrings remain direct FontStrings.
- Shared helpers audited for accidental fs.label/text.label/valueText.label corruption.

ADVANCED NPC RULE CONTROLS:
- Name color override
- Pick name color
- Special marker
- Show auras
- Show cast bar
- Execute warning
- Emphasize NPC
- De-emphasize NPC

ADVANCED SPELL RULE CONTROLS:
- Cast glow
- Cast pulse
- Flash near end
- Text warning

TEST:
1. /mnp opens without errors.
2. General page renders sliders/checks.
3. Every pre-existing page still renders.
4. Rules page opens.
5. NPC and Spell tabs work.
6. Add Current Target / Recently Seen still work.
7. Advanced toggles persist through /reload.
8. No Lua errors or taint.
