feat(DM): instant cache load, manual refresh, full-screen season selector, season persistence fix

- Cache loads synchronously on onShow for instant startup, no auto fetch
- Added manual Refresh button, removed auto refresh that blocked UI
- Made UI non-blocking during fetch (episode list usable while fetching)
- Fixed season loss after player/downloader by preserving season in static s_preserved_season surviving G memset
- Season selector now full-screen overlay parented to lv_scr_act()
- Removed DL Missing batch button and bottom help/status label per UX request
- load_state no longer overwrites browsing season with last_slug season

Apps/DiscoveryMountain/main/Source/player.c

@@ -37,6 +37,14 @@ static bool try_external_downloader(int idx) {
     char fpath[300];
     make_sd_path(fpath, sizeof(fpath), ep->slug);
 
+    // Preserve browsing season so we return to same season after downloader closes – survive G memset via static
+    dm_preserve_season(ep->season);
+    int saved_season = G.cur_season;
+    G.cur_season = ep->season;
+    save_state();
+    G.cur_ep_idx = idx;
+    (void)saved_season;
+
     tt_lvgl_lock(portMAX_DELAY);
     close_overlay();
     if(G.dl_overlay) hide_dl_overlay();
@@ -51,7 +59,7 @@ static bool try_external_downloader(int idx) {
     tt_bundle_put_string(b, "path", fpath);
     tt_bundle_put_bool(b, "override", false);
 
-    ESP_LOGI(TAG, "Starting external SdDownloader for %s -> %s", ep->slug, fpath);
+    ESP_LOGI(TAG, "Starting external SdDownloader for %s -> %s season %d", ep->slug, fpath, G.cur_season);
     G.pending_dl_idx = idx;
 
     tt_lvgl_lock(portMAX_DELAY);
@@ -118,6 +126,10 @@ bool download_missing_season_start(int season){
     G.dl_missing_total=missing;
     G.dl_missing_done=0;
     G.dl_missing_failed=0;
+    // Preserve season in persisted state and static before leaving
+    dm_preserve_season(season);
+    G.cur_season = season;
+    save_state();
     int first = find_next_missing_in_season(season);
     if(first==-1){
         G.dl_missing_active=false;
@@ -173,11 +185,12 @@ void start_idx_internal(int idx){
         tt_bundle_put_int32(b, "pos_sec", saved);
         tt_bundle_put_int32(b, "position", saved);
         tt_bundle_put_int32(b, "volume", G.volume);
-        ESP_LOGI(TAG, "Launching Mp3Player for %s pos %d", fpath, saved);
+        ESP_LOGI(TAG, "Launching Mp3Player for %s pos %d season %d", fpath, saved, ep->season);
         G.pending_dl_idx = idx;
         G.cur_ep_idx=idx; G.cur_season=ep->season;
         strncpy(G.cur_title,ep->title,sizeof(G.cur_title)-1);
         strncpy(G.last_slug,ep->slug,sizeof(G.last_slug)-1);
+        dm_preserve_season(ep->season);
         save_state();
         tt_app_start_with_bundle("one.tactility.mp3player", b);
         return;