[performance] move thumbnail generation to go code where possible (#3183)

* wrap thumbnailing code to handle generation natively where possible

* more code comments!

* add even more code comments!

* add code comments about blurhash generation

* maintain image rotation if contained in exif data

* move rotation before resizing

* ensure pix_fmt actually selected by ffprobe, check for alpha layer with gifs

* use linear instead of nearest-neighbour for resizing

* work with image "orientation" instead of "rotation". use default 75% quality for both webp and jpeg generation

* add header to new file

* use thumb extension when getting thumb mime type

* update test models and tests with new media processing

* add suggested code comments

* add note about thumbnail filter count reducing memory usage

internal/media/metadata.go

@@ -47,9 +47,14 @@ func clearMetadata(ctx context.Context, filepath string) error {
 		// cleaning exif data using a native Go library.
 		log.Debug(ctx, "cleaning with exif-terminator")
 		err := terminateExif(outpath, filepath, ext)
-		if err != nil {
-			return err
+		if err == nil {
+			// No problem.
+			break
 		}
+
+		log.Warnf(ctx, "error cleaning with exif-terminator, falling back to ffmpeg: %v", err)
+		fallthrough
+
 	default:
 		// For all other types, best-effort clean with ffmpeg.
 		log.Debug(ctx, "cleaning with ffmpeg -map_metadata -1")