Track content changes with activity log (FAQ/partners/sponsors)

[smnmsr]

Summary

Introduce audit logging for content edits related to:

• FAQs
• Partners
• Sponsors

Why

Admins should be able to answer who changed what and when, especially once CRUD forms are enabled.

Scope (future)

• Add spatie/laravel-activitylog
• Track create/update/delete events for FAQ, Partner, Sponsor models
• Include changed attributes in log payload
• Add an admin view (or temporary log access strategy) for inspection

Acceptance Criteria

• Content changes are recorded with user id, timestamp, model type/id
• Key changed fields are visible in the activity entry
• Logging does not impact public page performance

Notes

Deferred from current PR by design; current PR focuses on model/schema/backfill/datatable rollout.