feat: Implement user management with a new add_user binary and refactor state handling into a dedicated store module.

backend/src/store.rs

@@ -0,0 +1,46 @@
+use crate::items::{Game, Person};
+use serde::{Deserialize, Serialize};
+use std::fs::File;
+use std::io::BufReader;
+
+#[derive(Clone, Serialize, Deserialize)]
+pub struct User {
+    pub person: Person,
+    pub password_hash: String,
+}
+
+impl std::ops::Deref for User {
+    type Target = Person;
+
+    fn deref(&self) -> &Self::Target {
+        &self.person
+    }
+}
+
+#[derive(Serialize, Deserialize)]
+pub struct PersistentState {
+    pub games: Vec<Game>,
+    pub users: Vec<User>,
+}
+
+pub const STATE_FILE: &str = "state.json";
+
+pub fn save_state(games: &[Game], users: &[User]) {
+    let state = PersistentState {
+        games: games.to_vec(),
+        users: users.to_vec(),
+    };
+    if let Ok(file) = File::create(STATE_FILE) {
+        let _ = serde_json::to_writer_pretty(file, &state);
+    }
+}
+
+pub fn load_state() -> Option<(Vec<Game>, Vec<User>)> {
+    if let Ok(file) = File::open(STATE_FILE) {
+        let reader = BufReader::new(file);
+        if let Ok(state) = serde_json::from_reader::<_, PersistentState>(reader) {
+            return Some((state.games, state.users));
+        }
+    }
+    None
+}