[Enhancement] Misc. UI updates (#434)

* Format 'Scheduled At' in task table according to user's TZ

* Changed video preview layout to 1 column on all displays

* Made links in descriptions clickable

* Updated Copy JSON button to properly escape newline characters

lib/pinchflat_web/controllers/sources/source_html/actions_dropdown.html.heex

@@ -17,7 +17,7 @@
   <:option>
     <span x-data="{ copied: false }" x-on:click={~s"
         copyWithCallbacks(
-          `#{Jason.Formatter.pretty_print(Phoenix.json_library().encode!(@source))}`, 
+          String.raw`#{Jason.Formatter.pretty_print(Phoenix.json_library().encode!(@source))}`,
           () => copied = true, 
           () => copied = false
         )