Set default display behavior for image datatypes to inline preview

Image datatypes now display inline in dataset previews by default, with
browser-compatible formats like PNG and JPG showing previews instead of
download prompts. Specialized formats like proprietary microscopy and
medical imaging files still trigger downloads as appropriate.

Author: dannon

lib/galaxy/datatypes/images.py

@@ -65,6 +65,7 @@ class Image(data.Data):
     edam_data = "data_2968"
     edam_format = "format_3547"
     file_ext = ""
+    display_behavior = "inline"  # Most image formats can be displayed inline in browsers
 
     MetadataElement(
         name="axes",
@@ -419,18 +420,22 @@ def set_peek(self, dataset: DatasetProtocol, **kwd) -> None:
 
 class Hamamatsu(Image):
     file_ext = "vms"
+    display_behavior = "download"  # Proprietary microscopy format, not browser-displayable
 
 
 class Mirax(Image):
     file_ext = "mrxs"
+    display_behavior = "download"  # Proprietary microscopy format, not browser-displayable
 
 
 class Sakura(Image):
     file_ext = "svslide"
+    display_behavior = "download"  # Proprietary microscopy format, not browser-displayable
 
 
 class Nrrd(Image):
     file_ext = "nrrd"
+    display_behavior = "download"  # Medical imaging format, not browser-displayable
 
 
 class Bmp(Image):