refactored equipment pages underlying code

moved rendering of equipment thumbnails from referencing. repurposed front matter header info to using existing image info.
restored equipment front matter header info back to normal header instead of equipment images.
added header text to equipment pages missing it. (part of #28)
added 10px padding between equipment text and images (part of #28)
re-wrote underlying equipment code to allow the use of the default header once again without breaking things
removed old placeholder art files (closes #28)
updated 404.html to properly reference includes instead of manual code (closes #22)
doubled equipment image sizes to 500px (closes #16)

Latest commit:	`ba19a6e`
Status:	✅ Deploy successful!
Preview URL:	https://2e04ddea.synshop-org.pages.dev
Branch Preview URL:	https://nav-includes.synshop-org.pages.dev

synshop / synshop.org