Add sqlite for tracking build history.

src/config/root.rs

@@ -73,4 +73,11 @@ impl Config {
         let work_dir = current_dir.join("work");
         Ok(Cow::Owned(work_dir))
     }
+
+    /// The path to the sqlite database where run history is stored.
+    pub(crate) fn get_database_path(&self) -> Result<Cow<'_, Path>, CustomError> {
+        let output_directory = self.get_output_directory()?;
+        let database_path = output_directory.join("nix_builder.sqlite");
+        Ok(Cow::Owned(database_path))
+    }
 }