Library import asks for a location to file the cards under

After picking a file, Import cards… asks where the cards are kept,
pre-filled with the file's name (a ManaBox export is named after its
binder). A location is set on every imported card, replacing any it had,
as Add Cards does; blank leaves locations alone. It's applied inside the
import's single transaction.

src-tauri/src/commands.rs

@@ -441,11 +441,16 @@ pub struct LibraryImportProgress {
     pub total: usize,
 }
 
-/// Import a card list (plain text or a ManaBox export) into the library.
+/// Import a card list (plain text or a ManaBox export) into the library,
+/// filing every imported card under `location` unless it's blank.
 /// Runs on a blocking thread so the UI stays responsive, emitting
 /// `library-import-progress` as it goes.
 #[tauri::command]
-pub async fn import_library_cards(app: AppHandle, path: String) -> Res<LibraryImportResult> {
+pub async fn import_library_cards(
+    app: AppHandle,
+    path: String,
+    location: Option<String>,
+) -> Res<LibraryImportResult> {
     crate::sync::blocking(move || {
         let text = std::fs::read_to_string(&path).map_err(|e| e.to_string())?;
         let s = crate::sync::lock(&app);
@@ -453,7 +458,7 @@ pub async fn import_library_cards(app: AppHandle, path: String) -> Res<LibraryIm
         let mut last_percent = None;
         let (added, unresolved) = s
             .catalog()?
-            .import_card_list(&text, |done, total| {
+            .import_card_list(&text, location.as_deref().unwrap_or(""), |done, total| {
                 let percent = (done * 100).checked_div(total).unwrap_or(100);
                 if last_percent != Some(percent) {
                     last_percent = Some(percent);