Fix site config, duplicate headings, and code block copy button

[philip]

Minor tweaks while playing with the site:

• Set production URL to dev.databricks.com and update related org/project name config
• Fix duplicate ## headings in template markdown API by removing redundant heading injection (recipe files already include their own)
• Fix code blocks inside list items rendering as inline code by promoting language-* code elements to full CodeBlock components
• Fix code copy button positioned off-screen due to --ifm-pre-padding shorthand breaking Docusaurus's calc() positioning
• Suppress Docusaurus auto-opening the internal port during vercel dev