Determine if we need to change historic json schema type from string to number

#### Describe the task

In https://github.com/bcgov/cas-registration/pull/3490, we changed some form fields from type string to type number. We may need to do a migration to update the values that were previously strings.

Context:
- https://teams.microsoft.com/l/message/19:81544b60877c4a5eb4fc7946ecbcb525@thread.tacv2/1749665410152?tenantId=6fdb5200-3d0d-4a8a-b036-d3685e359adc&groupId=29821293-3244-455d-beae-e01d27762cfe&parentMessageId=1749665410152&teamName=External%3A%20CAS%20-%20Clean%20Growth%20Digital%20Service%20Team&channelName=Developers&createdTime=1749665410152&ngc=true
- https://teams.microsoft.com/l/message/19:81544b60877c4a5eb4fc7946ecbcb525@thread.tacv2/1750433661201?tenantId=6fdb5200-3d0d-4a8a-b036-d3685e359adc&groupId=29821293-3244-455d-beae-e01d27762cfe&parentMessageId=1750433661201&teamName=External%3A%20CAS%20-%20Clean%20Growth%20Digital%20Service%20Team&channelName=Developers&createdTime=1750433661201&ngc=true

#### Acceptance Criteria

- [ ] first
- [ ] second
- [ ] third

#### Definition of Done

- [ ] first
- [ ] second
- [ ] third

#### Additional context

- Add any other context about the task here.
- Or here

Review pull request #3490 first to identify the form fields whose schema types changed from string to number. Inspect how historic JSON values are stored and used, then determine whether a migration is required; document the decision and replace the placeholder acceptance criteria with concrete checks.

Written by the indexing model from the issue text.