feat(cms): add management for partnerships, history, accreditation, admissions, and policies pages

Implement a singleton page content system to manage static informational pages. This includes:
- New controllers, models, and data files for Partnerships, History, Accreditation, Admissions, and Policies.
- Admin routes and views for updating page content.
- Public API endpoints for fetching page data.
- Migration scripts for initializing page data.
- Updated admin navigation layout to include a dropdown for "About" sections.
- Audit action constants for tracking updates to these pages.

scripts/2026_04_20_122830_admissions.js

@@ -0,0 +1,8 @@
+const migrateSingletonPage = require("./_migrate-singleton-page");
+
+migrateSingletonPage({
+  migrationName: "import_admissions_content",
+  modelPath: "../models/admissionsPage",
+  dataFile: "admissions.json",
+  label: "Admissions",
+});