[v2.0] WebUI Refactor

[jaylikesbunda]

What's new (Author - fill this out)

• Complete WebUI refactor
• Dedicated webui/ directory for all WebUI source, build tooling, and mock host

Changed

• Moved html_to_header.py from scripts/site/ to webui/html_to_header.py

Removed

• scripts/site/ directory entirely (Dockerfile, build_html.sh, ghost_site.html, html_to_header.py, rollup config, node_modules)

Verification (Author - fill this out)

• I have tested Primary device(s) (list exact HW + config):
• I have tested potentially affected devices (and/or list potential affected devices not available to you):
• I have wrapped device specific code with #ifdef CONFIG_... or similar: [ ] Yes / [ ] N/A
• I have updated Hugo Docs with any new or changed info for end users: [ ] Yes / [ ] N/A

Linked Issues

• Closes #

Checklist (Reviewer - don't fill this out)

• Code builds, flashes, and feature verified with no functional issues on listed device(s)
• Changes reviewed for unintended impact on other devices/targets