appview/pages: add placeholder for when workflow logs are missing

Signed-off-by: oppiliappan <[e-mail]>

appview/pages/templates/repo/pipelines/workflow.html

···
        hx-ext="ws"
        ws-connect="/{{ $.RepoInfo.FullName }}/pipelines/{{ .Pipeline.Id }}/workflow/{{ .Workflow }}/logs">
     <div id="lines" class="flex flex-col gap-2">
+      <div class="text-base text-gray-500 flex items-center justify-center italic p-12 only:flex hidden border border-gray-200 dark:border-gray-700 rounded">
+        <span class="flex items-center gap-2">
+          {{ i "triangle-alert" "size-4" }} No logs for this workflow
+        </span>
+      </div>
     </div>
   </div>
 {{ end }}

spindle/models/logger.go

···
 }
 
 func (l *WorkflowLogger) DataWriter(stream string) io.Writer {
-	// TODO: emit stream
 	return &dataWriter{
 		logger: l,
 		stream: stream,