MidnightNameplates Phase 9.3.5 - Larger Config + Preview

- Main configuration window enlarged to 920 x 700.
- Live Preview canvas enlarged to 360 x 180.
- Preview stage enlarged while keeping actual nameplate dimensions controlled by settings.
- Built directly on the clean Phase 9.3.4 config restore.
- No rule engine, combat, aura, secure, or nameplate runtime logic changed.

Test:
1. /mnp opens at the larger size.
2. Live Preview has substantially more room.
3. General/Health/Name/etc pages still align.
4. Rules page and scrollbars still work.
5. No Lua errors.
