fix(settings): add category subfolders toggle

Add a Settings > Locations toggle that disables automatic category subfolders while keeping the selected base download folder as the automatic destination.

Persist the setting across frontend and backend startup paths and disable the category subfolder controls when the feature is off.

Fixes #6

src-tauri/src/download_ownership.rs

@@ -168,6 +168,9 @@ fn legacy_download_queue_paths(app_handle: &tauri::AppHandle) -> Result<Vec<Path
         }
 
         let category_destination = settings.as_ref().map(|settings| {
+            if !settings.category_subfolders_enabled {
+                return settings.base_download_folder.clone();
+            }
             settings
                 .category_directory_overrides
                 .get(&category)

src-tauri/src/ipc.rs

@@ -246,6 +246,7 @@ pub struct SchedulerSettings {
 pub struct PersistedSettings {
     pub theme: Theme,
     pub base_download_folder: String,
+    pub category_subfolders_enabled: bool,
     pub category_subfolders: HashMap<String, String>,
     pub category_directory_overrides: HashMap<String, String>,
     pub approved_download_roots: Vec<String>,

src-tauri/src/settings.rs

@@ -236,6 +236,9 @@ fn migrate_location_settings(state: &mut Value) -> Result<(), String> {
     }
 
     state.insert("baseDownloadFolder".to_string(), Value::String(base));
+    state
+        .entry("categorySubfoldersEnabled".to_string())
+        .or_insert(Value::Bool(true));
     state.insert(
         "categorySubfolders".to_string(),
         serde_json::to_value(subfolders)
@@ -268,6 +271,7 @@ fn default_settings() -> PersistedSettings {
     PersistedSettings {
         theme: Theme::System,
         base_download_folder: "~/Downloads".to_string(),
+        category_subfolders_enabled: true,
         category_subfolders: default_category_subfolders(),
         category_directory_overrides: HashMap::new(),
         approved_download_roots: Vec::new(),
@@ -378,6 +382,7 @@ mod tests {
             vec!["00000000-0000-0000-0000-000000000001"]
         );
         assert_eq!(settings.base_download_folder, "~/Downloads");
+        assert!(settings.category_subfolders_enabled);
     }
 
     #[test]
@@ -475,6 +480,25 @@ mod tests {
         assert_eq!(settings.category_subfolders["Documents"], "Documents");
     }
 
+    #[test]
+    fn decodes_disabled_category_subfolders() {
+        let stored = json!({
+            "state": {
+                "baseDownloadFolder": "/Users/test/Downloads",
+                "categorySubfoldersEnabled": false,
+                "categorySubfolders": {
+                    "Movies": "Movies"
+                }
+            },
+            "version": 3
+        });
+
+        let settings = decode_stored_settings(&Value::String(stored.to_string())).unwrap();
+
+        assert!(!settings.category_subfolders_enabled);
+        assert_eq!(settings.category_subfolders["Movies"], "Movies");
+    }
+
     #[test]
     fn replaces_zero_concurrency_with_the_safe_default() {
         let stored = json!({"state": {"maxConcurrentDownloads": 0}, "version": 0});