feat(web): persist exclusive reviewer duty on project create

Keep project_role as member/viewer, send document_duty=reviewer for USER_B, and clear the seed 李主管 reviewer so the assigned reviewer is the one that syncs.

Co-authored-by: Cursor <cursoragent@cursor.com>

web/src/api/projectMembers.ts

@@ -2,6 +2,7 @@ import { getBearerAuthHeaders } from './authHeaders';
 
 export type ApiProjectMemberRole = 'owner' | 'member' | 'viewer';
 export type ApiProjectMemberStatus = 'active' | 'exited';
+export type ApiDocumentDuty = 'author' | 'reviewer' | 'approver' | '';
 
 export interface ApiProjectMemberRecord {
   id?: number;
@@ -10,6 +11,7 @@ export interface ApiProjectMemberRecord {
   username?: string;
   name?: string;
   project_role: ApiProjectMemberRole;
+  document_duty?: ApiDocumentDuty;
   status: ApiProjectMemberStatus;
   joined_at?: string;
 }
@@ -21,6 +23,7 @@ export interface ListProjectMembersResponse {
 export interface UpsertProjectMemberPayload {
   user_id: number;
   project_role: ApiProjectMemberRole;
+  document_duty?: ApiDocumentDuty;
   status?: ApiProjectMemberStatus;
 }