Remove PayPal, simplify to QRIS-only with in-app QR display

- Remove PayPal payment option from checkout
- Add qr_string and qr_expires_at columns to orders table
- Update create-payment to store QR string in database
- Update pakasir-webhook to clear QR string after payment
- Simplify Checkout to redirect to order detail page
- Clean up unused imports and components

Flow:
1. User checks out with QRIS (only option)
2. Order created with payment_method='qris'
3. QR string stored in database
4. User redirected to Order Detail page
5. QR code displayed in-app with polling
6. After payment, QR string cleared, access granted

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

supabase/migrations/20241224_add_qr_string_to_orders.sql

@@ -0,0 +1,19 @@
+-- ============================================================================
+-- Add QR String Support to Orders
+-- ============================================================================
+-- Stores QRIS string and expiry for in-app QR code display
+-- Eliminates need to redirect to external payment page
+-- ============================================================================
+
+-- Add columns for QRIS payment data
+ALTER TABLE orders
+ADD COLUMN IF NOT EXISTS qr_string TEXT,
+ADD COLUMN IF NOT EXISTS qr_expires_at TIMESTAMPTZ;
+
+-- Add index for cleanup of expired QR codes
+CREATE INDEX IF NOT EXISTS idx_orders_qr_expires_at ON orders(qr_expires_at)
+WHERE qr_expires_at IS NOT NULL;
+
+-- Add comment
+COMMENT ON COLUMN orders.qr_string IS 'QRIS payment string for generating QR code in-app. Cleared after payment or expiration.';
+COMMENT ON COLUMN orders.qr_expires_at IS 'QRIS code expiration timestamp. Used for cleanup and validation.';