fix(storage): add panic recovery for malformed MP4 files

- Add defer/recover in getMP4Meta to catch panics from gomedia library
- Implement fallback to ffprobe when MP4 parsing fails
- Fixes "no vosdata" panic when processing certain MP4 files

Also add CLAUDE.md to provide architecture guidance for AI coding assistants.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

storage/telegram/telegram.go

@@ -181,6 +181,11 @@ func (t *Telegram) Save(ctx context.Context, r io.Reader, storagePath string) er
 		switch mtypeStr {
 		case "video/mp4":
 			info, err := getMP4Meta(rs)
+			if err != nil {
+				// Fallback to ffprobe if gomedia fails (e.g., malformed MP4)
+				rs.Seek(0, io.SeekStart)
+				info, err = getVideoMetadata(rs)
+			}
 			if err == nil {
 				media = doc.Video().
 					Duration(time.Duration(info.Duration)*time.Second).

storage/telegram/util.go

@@ -21,12 +21,19 @@ type VideoMetadata struct {
 }
 
 // a go native way to get mp4 video metadata
-func getMP4Meta(rs io.ReadSeeker) (*VideoMetadata, error) {
+func getMP4Meta(rs io.ReadSeeker) (metadata *VideoMetadata, err error) {
+	// Recover from panics in the gomedia library (e.g., "no vosdata" panic)
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("panic while parsing MP4: %v", r)
+		}
+	}()
+
 	d := mp4.CreateMp4Demuxer(rs)
 
-	tracks, err := d.ReadHead()
-	if err != nil {
-		return nil, err
+	tracks, e := d.ReadHead()
+	if e != nil {
+		return nil, e
 	}
 
 	for _, track := range tracks {