Remove dead Stripe integration

Stripe was wired up but never used:
- No STRIPE_SECRET_KEY in .env
- Card payment step had a 'simulated fallback' that pretended to charge
- Stripe fees (1.4% + 20p) contradict '100% goes to charity' brand promise
- Bank transfer is the primary rail, GoCardless (DD) is the secondary

Removed:
- src/lib/stripe.ts (Stripe client, checkout sessions, webhooks)
- src/app/api/stripe/checkout/route.ts
- src/app/api/stripe/webhook/route.ts
- src/app/p/[token]/steps/card-payment-step.tsx (263 lines)
- 'stripe' and '@stripe/stripe-js' npm packages
- Card option from PaymentStep (payment-step.tsx)
- Card references from confirmation-step.tsx, success/page.tsx
- Stripe from landing page integrations grid
- Stripe from privacy policy sub-processors
- Stripe from terms of service payment references

Type Rail changed: 'bank' | 'gocardless' | 'card' → 'bank' | 'gocardless'
Pledge flow bundle: 19.5kB → 18.2kB (-1.3kB)

Payment options donors now see:
1. Bank Transfer (recommended, zero fees)
2. Direct Debit via GoCardless (1% + 20p, hassle-free)

pledge-now-pay-later/src/lib/stripe.ts

@@ -1,127 +0,0 @@
-import Stripe from "stripe"
-
-let stripeClient: Stripe | null = null
-
-export function getStripe(): Stripe | null {
-  if (stripeClient) return stripeClient
-
-  const key = process.env.STRIPE_SECRET_KEY
-  if (!key || key === "sk_test_REPLACE_ME") return null
-
-  stripeClient = new Stripe(key, {
-    apiVersion: "2025-01-27.acacia" as Stripe.LatestApiVersion,
-    typescript: true,
-  })
-  return stripeClient
-}
-
-/**
- * Create a Stripe Checkout Session for a card payment.
- * Returns the checkout URL to redirect the donor to.
- */
-export async function createCheckoutSession(opts: {
-  amountPence: number
-  currency: string
-  pledgeId: string
-  reference: string
-  eventName: string
-  organizationName: string
-  donorEmail?: string
-  successUrl: string
-  cancelUrl: string
-}): Promise<{ sessionId: string; checkoutUrl: string } | null> {
-  const stripe = getStripe()
-  if (!stripe) return null
-
-  try {
-    const session = await stripe.checkout.sessions.create({
-      mode: "payment",
-      payment_method_types: ["card"],
-      line_items: [
-        {
-          price_data: {
-            currency: opts.currency.toLowerCase(),
-            unit_amount: opts.amountPence,
-            product_data: {
-              name: `Donation — ${opts.eventName}`,
-              description: `Pledge ref: ${opts.reference} to ${opts.organizationName}`,
-            },
-          },
-          quantity: 1,
-        },
-      ],
-      customer_email: opts.donorEmail || undefined,
-      metadata: {
-        pledge_id: opts.pledgeId,
-        reference: opts.reference,
-      },
-      success_url: opts.successUrl,
-      cancel_url: opts.cancelUrl,
-    })
-
-    return {
-      sessionId: session.id,
-      checkoutUrl: session.url!,
-    }
-  } catch (error) {
-    console.error("Stripe checkout session error:", error)
-    return null
-  }
-}
-
-/**
- * Create a Stripe Payment Intent for embedded payment (Stripe Elements).
- * Returns client secret for frontend confirmation.
- */
-export async function createPaymentIntent(opts: {
-  amountPence: number
-  currency: string
-  pledgeId: string
-  reference: string
-  donorEmail?: string
-}): Promise<{ clientSecret: string; paymentIntentId: string } | null> {
-  const stripe = getStripe()
-  if (!stripe) return null
-
-  try {
-    const pi = await stripe.paymentIntents.create({
-      amount: opts.amountPence,
-      currency: opts.currency.toLowerCase(),
-      metadata: {
-        pledge_id: opts.pledgeId,
-        reference: opts.reference,
-      },
-      receipt_email: opts.donorEmail || undefined,
-      automatic_payment_methods: {
-        enabled: true,
-      },
-    })
-
-    return {
-      clientSecret: pi.client_secret!,
-      paymentIntentId: pi.id,
-    }
-  } catch (error) {
-    console.error("Stripe payment intent error:", error)
-    return null
-  }
-}
-
-/**
- * Verify a Stripe webhook signature.
- */
-export function constructWebhookEvent(
-  body: string | Buffer,
-  signature: string
-): Stripe.Event | null {
-  const stripe = getStripe()
-  const secret = process.env.STRIPE_WEBHOOK_SECRET
-  if (!stripe || !secret || secret === "whsec_REPLACE_ME") return null
-
-  try {
-    return stripe.webhooks.constructEvent(body, signature, secret)
-  } catch (error) {
-    console.error("Stripe webhook signature verification failed:", error)
-    return null
-  }
-}