Add GET /api/v1/character/details with each image's change time

Returns every character image with when it was last changed, in Unix seconds,
so clients can cache the images and download only the ones that changed.

internal/server/misc_handler.go

@@ -57,6 +57,12 @@ func (s *Server) registerMisc(a huma.API) {
 		func(ctx context.Context, _ *struct{}) (*jsonBody[[]string], error) {
 			return ok(s.characters.List())
 		})
+	register(s, a, route{op: get("list-character-details", "/character/details", "characters",
+		"List characters with change times",
+		"Returns every character image with the time it was last changed, so clients can cache images and download only the changed ones.")},
+		func(ctx context.Context, _ *struct{}) (*jsonBody[[]backend.CharacterDetails], error) {
+			return ok(s.characters.ListDetails())
+		})
 	image := get("get-character", "/character", "characters", "Character image",
 		"Returns a character image.", http.StatusBadRequest, http.StatusNotFound)
 	image.Responses = fileResponses("The image", "image/png", "image/jpeg")