feat(files): launch MP3 player from file explorer, 28p header cache

- SupportedFiles: isSupportedAudioFile (.mp3/.wav/.ogg/.flac)
- View::viewFile: audio files start one.tactility.mp3player with
  file=<path> argv (CurrentAppCompat parses key=value pairs)
- es3c28p: add CONFIG_LV_IMAGE_HEADER_CACHE_DEF_CNT=16 for parity
  with es3c35p

Devices/es3c28p/device.properties

@@ -23,3 +23,4 @@ storage.userDataLocation=SD
 # Launcher clock and full-screen wallpaper
 sdkconfig.CONFIG_LV_FONT_MONTSERRAT_48=y
 sdkconfig.CONFIG_LV_CACHE_DEF_SIZE=1048576
+sdkconfig.CONFIG_LV_IMAGE_HEADER_CACHE_DEF_CNT=16

Tactility/Private/Tactility/app/files/SupportedFiles.h

@@ -7,5 +7,6 @@ namespace tt::app::files {
 bool isSupportedAppFile(const std::string& filename);
 bool isSupportedImageFile(const std::string& filename);
 bool isSupportedTextFile(const std::string& filename);
+bool isSupportedAudioFile(const std::string& filename);
 
 } // namespace

Tactility/Source/app/files/SupportedFiles.cpp

@@ -26,4 +26,12 @@ bool isSupportedTextFile(const std::string& filename) {
         filename_lower.ends_with(".properties");
 }
 
+bool isSupportedAudioFile(const std::string& filename) {
+    std::string filename_lower = string::lowercase(filename);
+    return filename_lower.ends_with(".mp3") ||
+        filename_lower.ends_with(".wav") ||
+        filename_lower.ends_with(".ogg") ||
+        filename_lower.ends_with(".flac");
+}
+
 } // namespace tt::app::filebrowser

Tactility/Source/app/files/View.cpp

@@ -1,6 +1,7 @@
 #include <app/event.h>
 #include <app/execute.h>
 #include <app/install.h>
+#include <app/start.h>
 #include <app/stream.h>
 
 #include <lvgl/lvgl.h>
@@ -204,6 +205,15 @@ void View::viewFile(const std::string& path, const std::string& filename) {
             // Remove forward slash, because we need a relative path
             notes::start(file_path.substr(1));
         }
+    } else if (isSupportedAudioFile(filename)) {
+        // External MP3 player reads argv as key=value pairs (see
+        // CurrentAppCompat tt_app_start_with_bundle): file=<path>
+        std::string file_arg = "file=" + file_path;
+        const char* argv[] = { file_arg.c_str() };
+        uint32_t instance_id = 0;
+        if (app_start("one.tactility.mp3player", 1, argv, &instance_id) != ERROR_NONE) {
+            LOG_W(TAG, "Failed to start MP3 player for %s", file_path.c_str());
+        }
     } else if (isExecutablePath(file_path)) {
         runFile(file_path);
     } else {