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.

views/admin/pageContent/partials/tab-pane.ejs

@@ -0,0 +1,12 @@
+<div class="tab-pane fade <%= activeTab === tab.key ? 'show active' : '' %>" id="<%= tab.key %>" role="tabpanel">
+  <div class="card border shadow-sm">
+    <div class="card-header bg-white">
+      <h6 class="mb-0">
+        <i class="<%= tab.icon %> me-2"></i><%= tab.label %>
+      </h6>
+    </div>
+    <div class="card-body p-4">
+      <div class="page-editor-section" data-section-key="<%= tab.key %>"></div>
+    </div>
+  </div>
+</div>