Add v0.0.3 MariaDB connection test

VERSION

@@ -1 +1 @@
-0.0.2
+0.0.3

backend/app.py

@@ -1,18 +1,31 @@
-from flask import Flask, render_template
+from flask import Flask
+from db import get_db_connection
 
-app = Flask(
-    __name__,
-    template_folder="../templates",
-    static_folder="../static",
-)
+app = Flask(__name__)
 
 @app.route("/")
 def index():
-    return render_template(
-        "base.html",
-        page_title="OTB Billing",
-        content="OTB Billing v0.0.1 is alive."
-    )
+    return "OTB Billing v0.0.3 running"
+
+@app.route("/dbtest")
+def dbtest():
+    try:
+        conn = get_db_connection()
+        cursor = conn.cursor()
+        cursor.execute("SELECT NOW()")
+        result = cursor.fetchone()
+        conn.close()
+
+        return f"""
+        <h1>Database Connection OK</h1>
+        <p>Server time: {result[0]}</p>
+        """
+
+    except Exception as e:
+        return f"""
+        <h1>Database Connection FAILED</h1>
+        <pre>{e}</pre>
+        """
         
 if __name__ == "__main__":
-    app.run(host="127.0.0.1", port=5050)
+    app.run(host="0.0.0.0", port=5050)

backend/config.py

@@ -0,0 +1,8 @@
+import os
+
+class Config:
+    DB_HOST = "127.0.0.1"
+    DB_PORT = 3306
+    DB_NAME = "otb_billing"
+    DB_USER = "otb_billing"
+    DB_PASSWORD = "!2Eas678"

backend/db.py

@@ -0,0 +1,11 @@
+import mysql.connector
+from config import Config
+
+def get_db_connection():
+    return mysql.connector.connect(
+        host=Config.DB_HOST,
+        port=Config.DB_PORT,
+        user=Config.DB_USER,
+        password=Config.DB_PASSWORD,
+        database=Config.DB_NAME
+    )