feat(1099): show payer EIN on church profile page and 1099-NEC PDF

Populate the PAYER's TIN (EIN) box in Form1099FormService.BuildCopyBHtml
from ChurchProfile.PayerEin (blank when null, matching prior behaviour).
Add payerEin field to ChurchProfileDto TS model (flows into
UpdateChurchProfileRequest via the existing Omit type) and a text input on
the Church Info tab of the church-profile settings page, mirroring the
Routing # field pattern. CSV left unchanged — adding a payer context line
would break the existing ExportFilingCsvAsync assertion (3 lines expected).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

APP/src/app/features/disbursement/models/disbursement.model.ts

@@ -48,7 +48,7 @@ export interface ChurchProfileDto {
   id: number; name: string; nameZh: string | null; phone: string | null;
   email: string | null; website: string | null; address: string | null; city: string | null;
   state: string | null; zipCode: string | null; bankName: string | null;
-  bankAccountNumber: string | null; bankRoutingNumber: string | null; nextCheckNumber: number;
+  bankAccountNumber: string | null; bankRoutingNumber: string | null; payerEin: string | null; nextCheckNumber: number;
   aiProvider: string;
   claudeModel: string | null; claudeApiKeyMasked: string | null;
   geminiModel: string | null; geminiApiKeyMasked: string | null;

APP/src/app/features/disbursement/pages/church-profile-page/church-profile-page.component.html

@@ -55,6 +55,10 @@
               Routing # / 路由號碼
               <kendo-textbox [(ngModel)]="model.bankRoutingNumber"></kendo-textbox>
             </label>
+            <label class="flex flex-col gap-1">
+              Payer EIN / 雇主識別號 (EIN)
+              <kendo-textbox [(ngModel)]="model.payerEin" placeholder="XX-XXXXXXX"></kendo-textbox>
+            </label>
             <label class="flex flex-col gap-1">
               Next Check # / 下一張支票號碼
               <kendo-numerictextbox [(ngModel)]="model.nextCheckNumber" [min]="1" [decimals]="0" format="#"></kendo-numerictextbox>