feat(site): refresh website and install experience

[lefoulkrod]

Summary

• rebuild the homepage around a clearer ownership-first narrative and real product workflows
• replace the disconnected installer chooser with responsive macOS, Windows, and Linux installation journeys at /install.html
• align About, Getting Started, Agents, Routines, Integrations, Local Models, and CLI documentation with the current desktop app and command surface
• apply the refreshed visual system across navigation, sections, cards, media, supporting pages, and the footer
• add responsive product/install imagery, an accessible in-page lightbox, and the current desktop app icon
• synchronize desktop release metadata during deployment while retaining checked-in fallback data

Why

The previous site mixed infrastructure-oriented positioning with overlapping sections, inconsistent enumeration, and installation/documentation paths that no longer matched the current desktop product. This refresh makes the desktop app the default, gives each page a clear purpose, and preserves omnideck's open-source, ownership, local control, and no-lock-in positioning.

User impact

• visitors get a shorter, more coherent homepage focused on useful work
• each operating system has one complete installation path with release links and checksums from generated data
• /downloads.html redirects to /install.html
• documentation uses the current Agents and Routines UI, actual integration permissions, current Ollama behavior, and the published CLI command surface
• legacy /docs/tasks.html and /docs/configuration.html URLs remain available through redirects
• Community now routes through the site before opening Slack

Validation

• ./arbor check
• ./arbor build --force — 38 pages built
• git diff --check
• desktop-release synchronization resolved v0.1.0-beta.8
• production-build Lighthouse: Performance 99, Accessibility 100, Best Practices 100, SEO 100, LCP 2.2s, CLS 0
• public review preview: https://don-queensland-bacteria-urgent.trycloudflare.com

Review notes

• the Linux application journey was captured from the exact public AppImage; the install page correctly promotes DEB and RPM packages
• macOS Gatekeeper and Windows SmartScreen screens document the actual unsigned preview-release behavior
• VM capture provenance is included in plans/vm-lab-install-capture-provenance.md