Add automatic generation of favourite buttons

favourite buttons are based on how often a good i added to list
finished implementing setting category
made number of days until button an environment variable

rebase on main and fix

ran cargo fmt

lib/src/lib.rs

@@ -7,9 +7,13 @@ pub struct Item {
 }
 
 #[derive(Serialize, Deserialize, Default, Debug, Clone)]
-
 pub struct ItemData {
     pub checked: bool,
     pub amount: i64,
-    // TODO: add number
+}
+
+#[derive(Serialize, Deserialize, Default, Debug, Clone)]
+pub struct ButtonItem {
+    pub name: String,
+    pub category: Option<String>,
 }