Fix financial double-counting, rebuild cashup accountability, and redesign the Reports page

Financial correctness (donation-leg model):
- Donations are no longer mutated when assigned to a registration; assignment now
  creates an immutable "leg" record referencing the original donation instead.
- Fixed several places where money was double-counted once a donation was partially
  or fully assigned (Payments, Revenue summary, Cashup reconciliation, Finance
  report, Profit report, Master Orders, Revenue Detailed).
- Payments now record who recorded them (recordedBy), separate from who they're for.

Cashup:
- Per-user cash denomination counting (optional, any time) replaces the single
  event-wide manual entry; the event's cash actual is the live sum of these counts.
- New "Payment accountability by staff member" breakdown across all methods, and a
  read-only "Report" tab that opens automatically once an event is closed.

Reports page redesign:
- New shell: sidebar of universal filters (events, date range, past/inactive/closed
  toggles), searchable/categorized report grid, and a popup viewer with
  Print/Email/Excel/WhatsApp actions plus an in-app Reporting Guide.
- Visual pass: colored stat tiles and bar charts on most reports, matching mockups.
- PDF exports (download/Print/Email/WhatsApp) now share a branded design mirroring
  the web report — colored header, stat tiles, bar chart, highlighted totals.
- Excel export now produces a styled .xlsx (via exceljs) instead of a plain CSV.
- Master Orders' "Donations made" table is now included in every export channel.

Bug fixes discovered while testing exports:
- Report emails now go through the shared, DB-configurable mail utility instead of
  a one-off transporter that ignored Site Settings SMTP config.
- WhatsApp report sends now surface the actual WAWP API error and auto-recover a
  disconnected session, instead of a bare axios status-code message.

Also: Admin-editable notification preference, richer Admin Registrations dashboard,
{{payment.link}} placeholder for Email/WhatsApp Attendees, and background
email/WhatsApp attendee sending.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/prisma/migrations/20260728060433_add_yoco_fee_fields_to_payment/migration.sql

@@ -0,0 +1,5 @@
+-- AlterTable
+ALTER TABLE "Payment" ADD COLUMN     "feeAmount" DOUBLE PRECISION,
+ADD COLUMN     "feeChannel" TEXT,
+ADD COLUMN     "feePayer" TEXT,
+ADD COLUMN     "feeRate" DOUBLE PRECISION;

backend/prisma/migrations/20260728065200_add_event_fee_payer_override/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "Event" ADD COLUMN     "feePayerOnline" TEXT;

backend/prisma/migrations/20260728070306_remove_fee_payer_fields/migration.sql

@@ -0,0 +1,12 @@
+/*
+  Warnings:
+
+  - You are about to drop the column `feePayerOnline` on the `Event` table. All the data in the column will be lost.
+  - You are about to drop the column `feePayer` on the `Payment` table. All the data in the column will be lost.
+
+*/
+-- AlterTable
+ALTER TABLE "Event" DROP COLUMN "feePayerOnline";
+
+-- AlterTable
+ALTER TABLE "Payment" DROP COLUMN "feePayer";

backend/prisma/migrations/20260728085349_add_fee_amount_to_cashup_line/migration.sql

@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "EventCashupLine" ADD COLUMN     "feeAmount" DOUBLE PRECISION;

backend/prisma/migrations/20260803132738_add_payment_recorded_by_and_indexes/migration.sql

@@ -0,0 +1,11 @@
+-- AlterTable
+ALTER TABLE "Payment" ADD COLUMN     "recordedById" TEXT;
+
+-- CreateIndex
+CREATE INDEX "Payment_recordedById_idx" ON "Payment"("recordedById");
+
+-- CreateIndex
+CREATE INDEX "Payment_originalPaymentId_idx" ON "Payment"("originalPaymentId");
+
+-- AddForeignKey
+ALTER TABLE "Payment" ADD CONSTRAINT "Payment_recordedById_fkey" FOREIGN KEY ("recordedById") REFERENCES "User"("id") ON DELETE SET NULL ON UPDATE CASCADE;

backend/prisma/migrations/20260804093754_add_person_cash_counts/migration.sql

@@ -0,0 +1,43 @@
+-- CreateTable
+CREATE TABLE "EventCashupPersonCount" (
+    "id" TEXT NOT NULL,
+    "eventId" TEXT NOT NULL,
+    "userId" TEXT NOT NULL,
+    "enteredById" TEXT,
+    "notes" TEXT,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+
+    CONSTRAINT "EventCashupPersonCount_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "EventCashupPersonCountDenomination" (
+    "id" TEXT NOT NULL,
+    "countId" TEXT NOT NULL,
+    "value" DOUBLE PRECISION NOT NULL,
+    "count" INTEGER NOT NULL,
+
+    CONSTRAINT "EventCashupPersonCountDenomination_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE INDEX "EventCashupPersonCount_eventId_idx" ON "EventCashupPersonCount"("eventId");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "EventCashupPersonCount_eventId_userId_key" ON "EventCashupPersonCount"("eventId", "userId");
+
+-- CreateIndex
+CREATE INDEX "EventCashupPersonCountDenomination_countId_idx" ON "EventCashupPersonCountDenomination"("countId");
+
+-- AddForeignKey
+ALTER TABLE "EventCashupPersonCount" ADD CONSTRAINT "EventCashupPersonCount_eventId_fkey" FOREIGN KEY ("eventId") REFERENCES "Event"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "EventCashupPersonCount" ADD CONSTRAINT "EventCashupPersonCount_userId_fkey" FOREIGN KEY ("userId") REFERENCES "User"("id") ON DELETE CASCADE ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "EventCashupPersonCount" ADD CONSTRAINT "EventCashupPersonCount_enteredById_fkey" FOREIGN KEY ("enteredById") REFERENCES "User"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "EventCashupPersonCountDenomination" ADD CONSTRAINT "EventCashupPersonCountDenomination_countId_fkey" FOREIGN KEY ("countId") REFERENCES "EventCashupPersonCount"("id") ON DELETE CASCADE ON UPDATE CASCADE;