feat(video-builder): adjust screenshot width scaling and add config option

Co-authored-by: Copilot <copilot@github.com>

manual/video_builder.py

@@ -170,7 +170,11 @@ class ManualVideoBuilder:
 
         # Step 6: Overlay screenshots
         print_step("🖼️ Overlaying screenshots...")
-        screenshot_width = int((self.W * 45) // 100)
+        # Scale background to final resolution FIRST to avoid scaling issues
+        background_clip = background_clip.filter("scale", self.W, self.H)
+        
+        screenshot_width_percent = self.config.get("screenshot_width_percent", 85)
+        screenshot_width = int((self.W * screenshot_width_percent) // 100)
         current_time = 0
 
         for s in clips:
@@ -185,9 +189,6 @@ class ManualVideoBuilder:
             )
             current_time += s["audio_duration"]
 
-        # Scale to final resolution
-        background_clip = background_clip.filter("scale", self.W, self.H)
-
         # Step 7: Render
         print_step("🎥 Rendering the video...")
         self.output_dir.mkdir(parents=True, exist_ok=True)

manual_main.py

@@ -50,6 +50,7 @@ MANUAL_DEFAULTS = {
     "background_audio_dir": "assets/backgrounds/audio",
     "background_audio_volume": 0.1,
     "max_video_length": 120,
+    "screenshot_width_percent": 85
 }
 
 # Full default settings.config that TTS engines and shared modules expect.