Add MariaDB integration and repositories

Introduce DB support and repos: add modules/database.js (connection pool + runDDL) and SQL DDL files (data/ddl/*) for servers, users, providers, identities and credentials. Add repository layers: users, servers, providers, identities, credentials. Update server.js to run DDL at startup. Update .env.example with DB settings and bump dependencies in package.json/package-lock.json (add mariadb, bump dotenv/helmet/path-to-regexp/zod and dev tool upgrades). Error handling and logging included for DDL and repo operations.

modules/database.js

@@ -0,0 +1,62 @@
+const mariadb = require("mariadb")
+const logger = require("./logger")
+const fs = require("fs/promises")
+const path = require("path")
+
+const dbConfig = {
+    host: process.env.DATABASE_HOST,
+    user: process.env.DATABASE_USER,
+    password: process.env.DATABASE_PASSWORD,
+    database: process.env.DATABASE_NAME,
+    acquireTimeout: 20000,
+    connectTimeout: 20000,
+    bigIntAsNumber: true,
+    insertIdAsNumber: true,
+    decimalAsNumber: true
+}
+
+const pool = mariadb.createPool({
+    ...dbConfig,
+    connectionLimit: Number(process.env.DATABASE_CONNECTION_LIMIT) || 10
+})
+
+async function runDDL() {
+    let conn
+    try {
+        conn = await mariadb.createConnection({
+            ...dbConfig,
+            multipleStatements: true
+        })
+
+        const ddlDir = path.join(process.cwd(), "data", "ddl")
+        const files = await fs.readdir(ddlDir)
+        
+        const sqlFiles = files
+            .filter(file => file.endsWith(".sql"))
+            .sort()
+
+        for (const file of sqlFiles) {
+            const filePath = path.join(ddlDir, file)
+            const sql = await fs.readFile(filePath, "utf-8")
+
+            if (sql.trim()) {
+                logger.log(`Execution of ${file.bold}`, ["DDL", "yellow"])
+                await conn.query(sql)
+            }
+        }
+        logger.log("Initialization of tables done.", ["DDL", "yellow"])
+    } catch (error) {
+        logger.error("Error while executing scripts :", ["DDL", "yellow"])
+        logger.error(error)
+        throw error
+    } finally {
+        if (conn) {
+            await conn.end()
+        }
+    }
+}
+
+module.exports = {
+    pool,
+    runDDL
+}