feat(thumbnails): register Nikon NRW and Sony SRF raw previews

Both are TIFF-based camera raw formats handled by the same generic walker;
NRW detection needs the reva mimetype mapping in opencloud-eu/reva#773, SRF is
already mapped. No sample files on hand for these two, added by format
structure alongside their verified siblings.

services/thumbnails/README.md

@@ -30,7 +30,7 @@ Thumbnails can be generated from the following source file types:
 -   tiff
 -   bmp
 -   txt
--   camera raw files: nef, cr2, pef, arw, sr2, dng
+-   camera raw files: nef, nrw, cr2, pef, arw, sr2, srf, dng
 
 For camera raw files the thumbnail is generated from the JPEG preview the camera embedded in the file, the raw sensor data itself is not developed. Raw files without an embedded preview cannot be thumbnailed.
 

services/thumbnails/pkg/preprocessor/preprocessor.go

@@ -345,10 +345,12 @@ func ForType(mimeType string, opts map[string]any) FileConverter {
 	case "audio/ogg":
 		return AudioDecoder{}
 	case "image/x-nikon-nef",
+		"image/x-nikon-nrw",
 		"image/x-canon-cr2",
 		"image/x-pentax-pef",
 		"image/x-sony-arw",
 		"image/x-sony-sr2",
+		"image/x-sony-srf",
 		"image/x-adobe-dng":
 		return RawTiffDecoder{}
 	default:

services/thumbnails/pkg/thumbnail/mimetypes.go

@@ -13,10 +13,12 @@ var (
 		"image/x-ms-bmp":                    {},
 		"image/tiff":                        {},
 		"image/x-nikon-nef":                 {},
+		"image/x-nikon-nrw":                 {},
 		"image/x-canon-cr2":                 {},
 		"image/x-pentax-pef":                {},
 		"image/x-sony-arw":                  {},
 		"image/x-sony-sr2":                  {},
+		"image/x-sony-srf":                  {},
 		"image/x-adobe-dng":                 {},
 		"text/plain":                        {},
 		"audio/flac":                        {},

services/thumbnails/pkg/thumbnail/mimetypes_vips.go

@@ -13,10 +13,12 @@ var (
 		"image/x-ms-bmp":                    {},
 		"image/tiff":                        {},
 		"image/x-nikon-nef":                 {},
+		"image/x-nikon-nrw":                 {},
 		"image/x-canon-cr2":                 {},
 		"image/x-pentax-pef":                {},
 		"image/x-sony-arw":                  {},
 		"image/x-sony-sr2":                  {},
+		"image/x-sony-srf":                  {},
 		"image/x-adobe-dng":                 {},
 		"text/plain":                        {},
 		"audio/flac":                        {},