fix(dashcam): add missing dash-col CSS rules, correct MOV mime type and range clamp

- yaris.css: add dash-col-size/date/upload hide rules on mobile (<576px),
  dash-col-file truncation on tablet, btn-icon-mobile label hide
- app.py: clamp byte2 to file_size-1 to prevent Content-Length mismatch;
  detect MIME from file extension (.mov -> video/quicktime)

Co-authored-by: Copilot <[email protected]>

app.py

@@ -150,16 +150,18 @@ def local_video_file():
     except FileNotFoundError:
         return jsonify(error=f"Local video not found: {relative_path}"), 404
 
+    ext = os.path.splitext(path)[1].lower()
+    mime_map = {".mp4": "video/mp4", ".mov": "video/quicktime", ".avi": "video/x-msvideo", ".mkv": "video/x-matroska"}
+    mime = mime_map.get(ext, "video/mp4")
+
     file_size = os.path.getsize(path)
-    mime = "video/mp4"
     range_header = request.headers.get("Range")
 
     if range_header:
-        # Parse "bytes=start-end"
-        byte1, byte2 = 0, None
         m = range_header.strip().replace("bytes=", "").split("-")
         byte1 = int(m[0]) if m[0] else 0
         byte2 = int(m[1]) if len(m) > 1 and m[1] else file_size - 1
+        byte2 = min(byte2, file_size - 1)
         length = byte2 - byte1 + 1
 
         def generate_range():