remove: eliminate file management and LittleFS-based filesystem, implement savegame management for JSON config slots with wear-leveling

Software/MainBoard/rust/src/webserver/get_json.rs

@@ -114,12 +114,39 @@ pub(crate) async fn get_version_web<T, const N: usize>(
     Ok(Some(serde_json::to_string(&get_version(&mut board).await)?))
 }
 
+/// Return the current in-memory config, or — when `saveidx` is `Some(idx)` —
+/// the JSON stored in save slot `idx`.
 pub(crate) async fn get_config<T, const N: usize>(
     _request: &mut Connection<'_, T, N>,
+    saveidx: Option<usize>,
+) -> FatResult<Option<String>> {
+    let mut board = BOARD_ACCESS.get().await.lock().await;
+    let json = match saveidx {
+        None => serde_json::to_string(board.board_hal.get_config())?,
+        Some(idx) => {
+             board.board_hal.get_esp().load_config_slot(idx).await?
+        }
+    };
+    Ok(Some(json))
+}
+
+/// Return a JSON array describing every valid save slot on flash.
+pub(crate) async fn list_saves<T, const N: usize>(
+    _request: &mut Connection<'_, T, N>,
 ) -> FatResult<Option<String>> {
     let mut board = BOARD_ACCESS.get().await.lock().await;
-    let json = serde_json::to_string(&board.board_hal.get_config())?;
-    Ok(Some(json))
+    let saves = board.board_hal.get_esp().list_saves().await?;
+    Ok(Some(serde_json::to_string(&saves)?))
+}
+
+/// Erase (delete) a single save slot by index.
+pub(crate) async fn delete_save<T, const N: usize>(
+    _request: &mut Connection<'_, T, N>,
+    idx: usize,
+) -> FatResult<Option<String>> {
+    let mut board = BOARD_ACCESS.get().await.lock().await;
+    board.board_hal.get_esp().delete_save_slot(idx).await?;
+    Ok(None)
 }
 
 pub(crate) async fn get_battery_state<T, const N: usize>(