Add metrics historical backfill scripts, fix up all new metrics calc queries and add combined script to run

inventory-server/old/metrics/utils/db.js

@@ -0,0 +1,39 @@
+const { Pool } = require('pg');
+const path = require('path');
+require('dotenv').config({ path: path.resolve(__dirname, '../../..', '.env') });
+
+// Database configuration
+const dbConfig = {
+    host: process.env.DB_HOST,
+    user: process.env.DB_USER,
+    password: process.env.DB_PASSWORD,
+    database: process.env.DB_NAME,
+    port: process.env.DB_PORT || 5432,
+    ssl: process.env.DB_SSL === 'true',
+    // Add performance optimizations
+    max: 10, // connection pool max size
+    idleTimeoutMillis: 30000,
+    connectionTimeoutMillis: 60000
+};
+
+// Create a single pool instance to be reused
+const pool = new Pool(dbConfig);
+
+// Add event handlers for pool
+pool.on('error', (err, client) => {
+    console.error('Unexpected error on idle client', err);
+});
+
+async function getConnection() {
+    return await pool.connect();
+}
+
+async function closePool() {
+    await pool.end();
+}
+
+module.exports = {
+    dbConfig,
+    getConnection,
+    closePool
+};