Add account settings page with options to update email, password and delete account

db.py

@@ -574,3 +574,27 @@ ORDER BY invocation_time DESC""", [http_function_id])
                LIMIT %s""",
             (user_id, limit)
         )
+
+    def update_user_password(self, user_id, new_password_hash):
+        """Update user's password"""
+        self.execute(
+            'UPDATE users SET password_hash=%s WHERE id=%s',
+            [new_password_hash, user_id],
+            commit=True
+        )
+
+    def update_user_email(self, user_id, new_email):
+        """Update user's email address"""
+        self.execute(
+            'UPDATE users SET email=%s WHERE id=%s',
+            [new_email, user_id],
+            commit=True
+        )
+
+    def delete_user(self, user_id):
+        """Delete a user account and all associated data"""
+        self.execute(
+            'DELETE FROM users WHERE id=%s',
+            [user_id],
+            commit=True
+        )