feat: Add fast startup fetch and background caching

- Add  for quick startup using first N feeds
- Add background thread for full fetch and caching
- Update  to use fast fetch
- Update docs and skills

engine/pipeline/params.py

@@ -32,7 +32,7 @@ class PipelineParams:
 
     # Camera config
     camera_mode: str = "vertical"
-    camera_speed: float = 1.0
+    camera_speed: float = 1.0  # Default speed
     camera_x: int = 0  # For horizontal scrolling
 
     # Effect config