Manic day hadn't had a chance to revisit this but I did manage to resolve the issue. The Hadron template actually has a placeholder for the header element called analytics. I was able to utilize the default custom html module to solve the problem.
Thanks all for replying. Failing the above solution I most likely would have just ended up building something ...
Good question and the "correct answer" as others have commented is that you probably need to use a plugin to do this properly.
The RocketTheme "Hadron" Gantry 4 template does allow a custom CSS file but does not provide any feature to include an external CSS or JS file.
You could avoid installing a plugin by adding the code via a custom HTML module. You ...
The category object is $this->category, not $this->item and params are a Registry object so no need for json_decode().
To show category params for each article based on that article's category, you need retrieve the category for each article:
$categoryParams = JCategories::...