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.

models/_createSingletonPageModel.js

@@ -0,0 +1,28 @@
+const mongoose = require("mongoose");
+const jsonHelper = require("../utils/jsonHelper");
+
+function createSingletonPageModel(modelName, collectionName, dataFileName) {
+  const schema = new mongoose.Schema(
+    {},
+    {
+      strict: false,
+      timestamps: true,
+      collection: collectionName,
+    },
+  );
+
+  schema.statics.getSingle = async function getSingle() {
+    let doc = await this.findOne();
+
+    if (!doc) {
+      const defaultData = jsonHelper.readJsonFile(dataFileName) || {};
+      doc = await this.create(defaultData);
+    }
+
+    return doc;
+  };
+
+  return mongoose.model(modelName, schema);
+}
+
+module.exports = createSingletonPageModel;