feat: 支持合同专用章

packages/shared/src/types/contract.ts

@@ -30,6 +30,8 @@ export interface ContractDocument {
   readonly cardRows: readonly ContractRow[]
   readonly sections: readonly ContractSection[]
   readonly commitment: string
+  /** 乙方合同章图片，随正文及摘要冻结；旧合同可能没有。 */
+  readonly partyBSeal?: string
 }
 
 export interface ContractSignatureInfo {
@@ -106,6 +108,7 @@ export interface ContractPartyConfig {
   readonly standardLessonPrice: number
   readonly standardLessonPriceConfigured: boolean
   readonly signatureImage: string | null
+  readonly sealImage: string
   readonly signatureUpdatedAt: string | null
   readonly missingFields: readonly string[]
 }