fix: BCBS MA — identify patient by member ID + DOB, prevent overwriting subscriber

- Added getPatientByInsuranceIdAndDob to storage
- Processor uses insuranceId + DOB as unique key instead of insuranceId alone
- Dependent with same subscriber ID but different DOB gets a new patient record
  (bypasses createOrUpdatePatientByInsuranceId which would overwrite subscriber)
- Name extraction anchored to "Relationship:" to scope Patient Info column only

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/Backend/src/storage/patients-storage.ts

@@ -10,6 +10,7 @@ export interface IStorage {
   // Patient methods
   getPatient(id: number): Promise<Patient | undefined>;
   getPatientByInsuranceId(insuranceId: string): Promise<Patient | null>;
+  getPatientByInsuranceIdAndDob(insuranceId: string, dob: Date): Promise<Patient | null>;
   getAllPatients(): Promise<Patient[]>;
   getRecentPatients(limit: number, offset: number): Promise<Patient[]>;
   getPatientsByIds(ids: number[]): Promise<Patient[]>;
@@ -60,6 +61,19 @@ export const patientsStorage: IStorage = {
     });
   },
 
+  async getPatientByInsuranceIdAndDob(insuranceId: string, dob: Date): Promise<Patient | null> {
+    const startOfDay = new Date(dob);
+    startOfDay.setHours(0, 0, 0, 0);
+    const endOfDay = new Date(dob);
+    endOfDay.setHours(23, 59, 59, 999);
+    return db.patient.findFirst({
+      where: {
+        insuranceId,
+        dateOfBirth: { gte: startOfDay, lte: endOfDay },
+      },
+    });
+  },
+
   async getRecentPatients(limit: number, offset: number): Promise<Patient[]> {
     return db.patient.findMany({
       skip: offset,