[feature] Allow user to choose "gallery" style layout for web view of profile (#3917)

* [feature] Allow user to choose "gallery" style web layout

* find a bug and squish it up and all day long you'll have good luck

* just a sec

* [performance] reindex public timeline + tinker with query a bit

* fiddling

* should be good now

* last bit of finagling, i'm done now i prommy

* panic normally

internal/api/model/attachment.go

@@ -136,6 +136,10 @@ type WebAttachment struct {
 	// MIME type of
 	// the thumbnail.
 	PreviewMIMEType string
+
+	// Link to the URL of the parent
+	// status of this attachment.
+	ParentStatusLink string
 }
 
 // MediaMeta models media metadata.