add register, login and main page with basic functionality

app/db.py

@@ -0,0 +1,35 @@
+import sqlite3
+from flask import g
+
+DATABASE = 'sqlite.db'
+
+def get_db():
+    if 'db' not in g:
+        g.db = sqlite3.connect(DATABASE)
+        g.db.row_factory = sqlite3.Row
+    return g.db
+
+def close_db(e=None):
+    db = g.pop('db', None)
+
+    if db is not None:
+        db.close()
+
+def init_db(app):
+    with app.app_context():
+        db = get_db()
+        db.execute("PRAGMA journal_mode=WAL;")
+        db.execute("PRAGMA foreign_keys=ON;")
+
+        # create inital tables
+        db.execute("""
+        CREATE TABLE IF NOT EXISTS users (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,username TEXT UNIQUE NOT NULL,
+        password TEXT NOT NULL,
+        created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+        );
+        """
+        )
+
+
+        db.commit()