Move database to a permanent location

.gitignore

@@ -0,0 +1 @@
+quotes.db

backend/quote.py

@@ -1,3 +1,5 @@
+import os
+
 import marshmallow
 import sqlalchemy
 import sqlalchemy.orm
@@ -6,7 +8,9 @@ import sqlalchemy.ext.declarative
 from datetime import datetime
 
 
-engine = sqlalchemy.create_engine('sqlite:////tmp/quotes.db')  # FIXME
+DB_PATH = os.path.expandvars('$HOME/quotes/quotes.db')
+
+engine = sqlalchemy.create_engine(f'sqlite:///{DB_PATH}')
 Session = sqlalchemy.orm.sessionmaker(bind=engine)
 Base = sqlalchemy.ext.declarative.declarative_base()