As a user I want to file a standalone Director Change and choose any(that doesn't conflict) past date for the filing

Given I am logged in and have clicked on edit my directors
When I want to pick a date other than the CURRENT date displayed in the date picker
Then I want to choose a past date that doesn't conflict with ANY previous filing

## Description:

**Dependencies**

**Acceptance Criteria**

**Validation Rules**

Ready to Build (DoR):
- [ ] Stakeholders have approved
- [ ] User story completed
- [ ] What are the dependencies
- [ ] Validation rules defined (UI, Data, Role-Action)
- [ ] Is a formal UAT required

Acceptance / DoD:
- [ ] Design / Solution accepted by Product Owner
- [ ] Acceptance criteria has been defined (happy path, known sad paths)
- [ ] Test coverage acceptable
- [ ] Peer Reviewed
- [ ] Accessibility reviewed and acceptable [checklist](https://github.com/bcgov/entity/docs/coding-standards/accessibility.md)
- [ ] UX Approved
- [ ] PR Accepted
- [ ] Production burn in completed

No implementation file or test is named. Start by tracing the “edit my directors” flow and its date picker, then identify how previous filings are checked. Done means a logged-in user can file a standalone Director Change using a non-conflicting past date, with the relevant validation and test coverage in place.

Written by the indexing model from the issue text.