simplify: zakat yes/no per campaign, remove 5 fund types, add I've Donated button for external pledges

- Event.zakatEligible (boolean) replaces Organization.zakatEnabled + 5 fund types
- Pledge.isZakat (boolean) replaces Pledge.fundType enum
- Removed fundAllocation from Event (campaign IS the allocation)
- Identity step: simple checkbox instead of 5-option grid
- Campaign creation: Zakat toggle + optional external URL for self-payment
- External redirect step: 'I've Donated' button calls /api/pledges/[id]/mark-initiated
- Landing page: simplified Zakat section (toggle preview, not 5 fund descriptions)
- Settings: removed org-level Zakat toggle (it's per campaign now)
- Migration: ALTER TABLE adds zakatEligible/isZakat, drops fundAllocation

pledge-now-pay-later/src/app/p/[token]/page.tsx

@@ -21,7 +21,7 @@ export interface PledgeData {
   donorEmail: string
   donorPhone: string
   giftAid: boolean
-  fundType?: string
+  isZakat: boolean
   // Scheduling
   scheduleMode: "now" | "date" | "installments"
   dueDate?: string
@@ -38,8 +38,7 @@ interface EventInfo {
   paymentMode: "self" | "external"
   externalUrl: string | null
   externalPlatform: string | null
-  zakatEnabled: boolean
-  fundAllocation: string | null
+  zakatEligible: boolean
 }
 
 /*
@@ -66,6 +65,7 @@ export default function PledgePage() {
     donorEmail: "",
     donorPhone: "",
     giftAid: false,
+    isZakat: false,
     scheduleMode: "now",
   })
   const [pledgeResult, setPledgeResult] = useState<{
@@ -137,7 +137,7 @@ export default function PledgePage() {
   }
 
   // Submit pledge (from identity step, or card/DD steps)
-  const submitPledge = async (identity: { donorName: string; donorEmail: string; donorPhone: string; giftAid: boolean; fundType?: string }) => {
+  const submitPledge = async (identity: { donorName: string; donorEmail: string; donorPhone: string; giftAid: boolean; isZakat?: boolean }) => {
     const finalData = { ...pledgeData, ...identity }
     setPledgeData(finalData)
 
@@ -149,7 +149,7 @@ export default function PledgePage() {
           ...finalData,
           eventId: eventInfo?.id,
           qrSourceId: eventInfo?.qrSourceId,
-          fundType: finalData.fundType || undefined,
+          isZakat: finalData.isZakat || false,
         }),
       })
       const result = await res.json()
@@ -209,7 +209,7 @@ export default function PledgePage() {
     0: <AmountStep onSelect={handleAmountSelected} eventName={eventInfo?.name || ""} eventId={eventInfo?.id} />,
     1: <ScheduleStep amount={pledgeData.amountPence} onSelect={handleScheduleSelected} />,
     2: <PaymentStep onSelect={handleRailSelected} amount={pledgeData.amountPence} />,
-    3: <IdentityStep onSubmit={submitPledge} amount={pledgeData.amountPence} zakatEnabled={eventInfo?.zakatEnabled} fundAllocation={eventInfo?.fundAllocation} />,
+    3: <IdentityStep onSubmit={submitPledge} amount={pledgeData.amountPence} zakatEligible={eventInfo?.zakatEligible} />,
     4: pledgeResult && <BankInstructionsStep pledge={pledgeResult} amount={pledgeData.amountPence} eventName={eventInfo?.name || ""} donorPhone={pledgeData.donorPhone} />,
     5: pledgeResult && (
       <ConfirmationStep