fix(backend): raise burned subtitle placement

backend/app/services/clips.py

@@ -114,5 +114,15 @@ class ClipGenerator:
 
     def _subtitle_filter(self, subtitle_path: Path) -> str:
         escaped = str(subtitle_path.resolve()).replace("\\", "/").replace(":", "\\:")
-        style = "Fontname=Arial,Fontsize=18,PrimaryColour=&H00FFFFFF,OutlineColour=&H00000000"
+        style = (
+            "Fontname=Arial,"
+            "Fontsize=22,"
+            "PrimaryColour=&H00FFFFFF,"
+            "OutlineColour=&H00000000,"
+            "BorderStyle=1,"
+            "Outline=2,"
+            "Shadow=1,"
+            "Alignment=2,"
+            "MarginV=210"
+        )
         return f"subtitles='{escaped}':force_style='{style}'"