refactor(db): replace connectDb import paths and introduce new connect module

- Updated import paths for connectDb across various files to use the new centralized connect module.
- Removed the old connectDb file to streamline the database connection logic.
- Ensured all tests and models reference the new connection method for consistency.

api/lib/db/connectDb.js

@@ -1,57 +0,0 @@
-require('dotenv').config();
-const mongoose = require('mongoose');
-
-if (!process.env.MONGO_URI) {
-  throw new Error('Please define the MONGO_URI environment variable');
-}
-
-/**
- * Global is used here to maintain a cached connection across hot reloads
- * in development. This prevents connections growing exponentially
- * during API Route usage.
- */
-let cached = global.mongoose;
-
-if (!cached) {
-  cached = global.mongoose = { conn: null, promise: null };
-}
-
-async function connectDb(mongoUri = process.env.MONGO_URI) {
-  if (cached.conn && cached.conn?._readyState === 1) {
-    return cached.conn;
-  }
-
-  const disconnected = cached.conn && cached.conn?._readyState !== 1;
-  if (!cached.promise || disconnected) {
-    const opts = {
-      bufferCommands: false,
-      // useNewUrlParser: true,
-      // useUnifiedTopology: true,
-      // bufferMaxEntries: 0,
-      // useFindAndModify: true,
-      // useCreateIndex: true
-    };
-
-    mongoose.set('strictQuery', true);
-    cached.promise = mongoose.connect(mongoUri, opts).then((mongoose) => {
-      return mongoose;
-    });
-  }
-  cached.conn = await cached.promise;
-
-  return cached.conn;
-}
-
-function getModels() {
-  return cached.models;
-}
-module.exports = {
-  connectDb,
-  getModels,
-  get models() {
-    if (!cached.models) {
-      throw new Error('Models not registered. ');
-    }
-    return cached.models;
-  },
-};