Lower Give platform fee from 5% to 3.5%.

Update checkout constant, payout copy, and Afia prompts to match the new Ladill Pay rate.

Co-authored-by: Cursor <cursoragent@cursor.com>

DEPLOY.md

@@ -2,7 +2,7 @@
 
 Standalone app for **online giving pages** at `give.ladill.com` — branded donation
 pages with collection categories (Offering, Tithe, Building Fund…). Donations
-settle into the one platform UserWallet (5% fee), then withdraw via
+settle into the one platform UserWallet (3.5% fee), then withdraw via
 `account.ladill.com`.
 
 Public scans stay at `ladill.com/q/<code>` (blueprint decision — printed codes
@@ -24,7 +24,7 @@ main app DB user.
 |---|---|
 | `LADILL_SSO_CLIENT_ID` / `LADILL_SSO_CLIENT_SECRET` | `passport:client` on platform |
 | `BILLING_API_KEY_GIVE` | platform `.env` + this app |
-| `PAY_API_KEY_GIVE` | platform `.env` + this app — Ladill Pay checkout (5% donations tier) |
+| `PAY_API_KEY_GIVE` | platform `.env` + this app — Ladill Pay checkout (3.5% donations tier) |
 | `IDENTITY_API_KEY_GIVE` | platform `.env` + this app |
 | `PLATFORM_DB_*` | read `ladilldb.platform_settings` (Paystack keys from admin → Billing) |
 
@@ -84,7 +84,7 @@ php artisan config:cache route:cache view:cache
 
 - SSO login at `give.ladill.com`
 - Create a giving page, download QR PNG
-- Scan `/q/<code>`, give test amount, confirm wallet credit (net of 5%)
+- Scan `/q/<code>`, give test amount, confirm wallet credit (net of 3.5%)
 - Withdraw from `account.ladill.com/wallet`
 
 ## Product IA (blueprint)