Write Landing Docs

• Public website documentation is authored under docs/**.
• Read the Voice & Content section of ../../../DESIGN.md before drafting.
• For docs/self-hosting/**, read Default Audience.
• Verify claims, defaults, commands, limitations, and rollback behavior from current code.
• Prefer one canonical page, a recommended path, short executable steps, and a visible verification result. Keep English and Simplified Chinese versions aligned.
• If a published path changes, update internal links and add a tested permanent redirect in the landing repository that preserves locale prefixes and query parameters.
• Run the focused documentation check for every changed page.

For docs/changelog/**, use ../docs-changelog/SKILL.md instead.