Prestige Barber Club v4.44.13 - No Membership Creation Discount

Audit scope:
- Penjualan Member reguler
- Pembayaran calon member / Pra-Member
- Quick Membership POS
- Membership di transaksi POS gabungan
- Settings/Branding diskon pembuatan member
- Dashboard/riwayat membership effective net

Policy enforced:
1. Aktivasi/perpanjangan membership tidak memiliki diskon pembuatan.
2. Diskon manual pada harga membership dinonaktifkan untuk transaksi baru.
3. Diskon benefit level hanya berlaku pada jasa/produk.
4. Item membership dikeluarkan dari discount_base transaksi gabungan POS.
5. Harga membership transaksi baru = harga membership global/seragam.
6. Histori lama tidak dimutasi oleh upgrade.

Validation:
- PHP lint: 262 files, 0 syntax errors.
- Membership creation discount inputs removed from critical UIs.
- Server-side create_membership_sale_v435 forces card/manual discount = 0.
- POS server and JavaScript exclude membership amount from member discount base.