chore: Replace any with number in missedAppointmentsCount type

[pggdev]

Requirements

• This PR has a title that briefly describes the work done including the ticket number. If there is a ticket, make sure your PR title includes a conventional commit label. See existing PR titles for inspiration.
• My work is based on designs, which are linked or shown either in the Jira ticket or the description below.
• My work includes tests or is validated by existing tests.

Summary

This PR improves type safety in the appointments module by replacing an incorrect any type with a more specific and appropriate type.

The change resolves a TypeScript type error and ensures stronger compile-time validation without affecting runtime behavior.

No functional or UI changes were introduced.

Screenshots

N/A – No UI changes.

Related Issue

https://openmrs.atlassian.net/browse/O3-5451

Other

This is a small internal improvement focused on maintaining type correctness and improving overall code quality.

[pggdev]

@jayasanka-sack @ibacher @denniskigen please have a look at this!

[ibacher]

1. Please look at how we do conventional commits in this repo and elsewhere
2. Please fill in the PR form. It's there to collect information that helps us review things.