Perf: Optimize playback and simplify playlist management

- Performance improvements:
  * Throttle drawing updates to 60fps (16ms intervals)
  * Optimize file I/O: use single os.stat() instead of exists+getsize
  * Reduce logger overhead: convert hot-path info logs to debug
  * Preload next media asynchronously for smoother transitions
  * Smart cache invalidation for edited images

- Simplify playlist management:
  * Remove versioning: single server_playlist.json file
  * Create nested directories for edited_media downloads
  * Recursively delete unused media and empty folders
  * Cleaner version tracking without file proliferation

- UI improvements:
  * Smoother intro-to-playlist transition
  * Fix edited media directory creation for nested paths

src/edit_popup.py

@@ -30,6 +30,8 @@ class DrawingLayer(Widget):
         self.current_width = 3  # Default thickness
         self.drawing_enabled = True  # Drawing always enabled in edit mode
         self.reset_callback = reset_callback  # Callback to reset countdown timer
+        self._last_draw_time = 0  # For throttling touch updates
+        self._draw_throttle_interval = 0.016  # ~60fps (16ms between updates)
     
     def on_touch_down(self, touch):
         if not self.drawing_enabled or not self.collide_point(*touch.pos):
@@ -48,7 +50,11 @@ class DrawingLayer(Widget):
     
     def on_touch_move(self, touch):
         if 'line' in touch.ud and self.drawing_enabled:
-            touch.ud['line'].points += [touch.x, touch.y]
+            # Throttle updates to ~60fps for better performance
+            current_time = time.time()
+            if current_time - self._last_draw_time >= self._draw_throttle_interval:
+                touch.ud['line'].points += [touch.x, touch.y]
+                self._last_draw_time = current_time
         return True
     
     def undo(self):
@@ -68,12 +74,10 @@ class DrawingLayer(Widget):
     def set_color(self, color_tuple):
         """Set drawing color (RGBA)"""
         self.current_color = color_tuple
-        Logger.debug(f"DrawingLayer: Color set to {color_tuple}")
     
     def set_thickness(self, value):
         """Set line thickness"""
         self.current_width = value
-        Logger.debug(f"DrawingLayer: Thickness set to {value}")
 
 
 class EditPopup(Popup):