Add Check-in / Ice / Banquet scan modes

- Ice mode: prepaid ice bags (Ice Total / Ice Redeemed columns) redeemed
  independently of ticket check-ins; grab all bags at once or some now.
- Banquet mode: donor total (online + offline) looked up by the ticket's
  email via the Donors Master List, with a manual email override. New
  DonorService + POST /api/banquet.
- Redeem generalized over a resource (tickets|ice); audit records ice actions.
- App gains a mode selector; webhook maps ice_bags (defaults to
  ICE_BAGS_DEFAULT when only a boolean ice option is present).

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

backend/src/fields.ts

@@ -24,6 +24,8 @@ export const COL = {
   redeemed: "Redeemed",
   submissionKey: "SubmissionKey",
   lastScanAt: "LastScanAt",
+  iceTotal: "Ice Total", // prepaid ice bags
+  iceRedeemed: "Ice Redeemed", // bags picked up
 } as const;
 
 /** Age-bracket columns, in order. */
@@ -74,6 +76,12 @@ export function ageBreakdown(rec: NocoRecord): { bracket: string; count: number;
   })).filter((b) => b.count > 0);
 }
 
+export interface ResourceCount {
+  total: number;
+  redeemed: number;
+  remaining: number;
+}
+
 export interface TicketView {
   code: string;
   name: string;
@@ -81,6 +89,7 @@ export interface TicketView {
   total: number;
   redeemed: number;
   remaining: number;
+  ice: ResourceCount;
   extras: {
     carParking: boolean;
     rvParking: boolean;
@@ -91,9 +100,15 @@ export interface TicketView {
   ages: { bracket: string; count: number; free: boolean }[];
 }
 
+export function computeIceTotal(rec: NocoRecord): number {
+  return num(rec[COL.iceTotal]);
+}
+
 export function toView(rec: NocoRecord): TicketView {
   const total = computeTotal(rec);
   const redeemed = num(rec[COL.redeemed]);
+  const iceTotal = computeIceTotal(rec);
+  const iceRedeemed = num(rec[COL.iceRedeemed]);
   return {
     code: String(rec[COL.code] ?? ""),
     name: String(rec[COL.name] ?? ""),
@@ -101,6 +116,11 @@ export function toView(rec: NocoRecord): TicketView {
     total,
     redeemed,
     remaining: Math.max(0, total - redeemed),
+    ice: {
+      total: iceTotal,
+      redeemed: iceRedeemed,
+      remaining: Math.max(0, iceTotal - iceRedeemed),
+    },
     extras: {
       carParking: bool(rec[COL.carParking]),
       rvParking: bool(rec[COL.rvParking]),