feature: add allergies field to patient record

[devin-ai-integration]

Summary

Adds a free-text allergies field to the patient record, distinct from the existing structured allergies table (domain/clinical/Allergy): this is a simple demographic-level note captured at registration.

• V4__add_patient_allergies.sql: ALTER TABLE patients ADD COLUMN allergies TEXT;
• Patient.allergies (@Column(columnDefinition = "TEXT")) and PatientDTO.allergies — MapStruct PatientMapper picks it up by name, so POST/PUT /v1/patients and all reads now round-trip allergies with no controller/service changes.

Companion web PR: COG-GTM/demos-coghealth-ehr-web#76

Devin-Org: engineering

Link to Devin session: https://app.devin.ai/sessions/ce44618dd766405e8e37b4073bb21c37
Open in Devin Desktop: https://app.devin.ai/desktop/session/ce44618dd766405e8e37b4073bb21c37?variant=devin
Requested by: @rushcromer

[devin-ai-integration]

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