Add date and time stamp to discharge notifications that are sent to secured parties

### Context:
The ticket was raised in response to feedback from Jeff, who noted that discharge notifications currently lack a date and time stamp. This absence makes it difficult to determine exactly when a discharge occurred.

This enhancement addresses a gap identified by internal stakeholders, where discharge notifications currently lack a clear indication of when the discharge was processed. By including a standardized timestamp in both the notification and system records, the change will support audit readiness, improve communication with secure parties, and align with best practices for digital recordkeeping. The feature will apply to all new discharge notifications going forward, while preserving the integrity of historical records.

please refer to the parent ticket #29257 for details (business rules etc.)

### User Story
As a registry analyst or secure party recipient
I want discharge notifications to include the exact date and time the discharge was processed
So that I can verify when the discharge occurred and maintain accurate records for compliance and audit purposes

### Acceptance Criteria:
**Scenario:** Include timestamp in discharge notification
Given a discharge is processed by the system
When the discharge notification is generated
Then the notification should include the exact date and time the discharge occurred

**Scenario:** Timestamp follows standard format
Given a discharge notification is generated
When the timestamp is added
Then it should follow the format "YYYY-MM-DD HH:MM" in the local time zone

**Scenario:** Timestamp is visible in the UI
Given I am a registry analyst
When viewing a discharge notification
Then I should see the timestamp clearly displayed in the notification details

**Scenario:** Timestamp is stored in system logs
Given I am a registry analyst
When processing a discharge
Then the timestamp should be stored in the system for audit and support purposes

**Scenario:** Older discharge notifications remain unchanged
Given a discharge notification was generated before the timestamp feature was implemented
When the notification is viewed or retrieved
Then the notification should not include a timestamp
And only discharge notifications generated after the implementation date should include the timestamp
Business Rules and Requirements are posted [here](https://docs.google.com/document/d/1knTjS5pOnqrS7z4r4o8WozI9TXCy94xl/edit)

No files, tests, or entry points are named. Start by locating discharge notification generation, notification details in the UI, and the system record or audit-log path, then review the linked business rules. Done means new notifications show the discharge timestamp as YYYY-MM-DD HH:MM in local time, it is stored for audit purposes, and older notifications remain unchanged.

Written by the indexing model from the issue text.