[littleben]

Summary

• Preserve referrers for allowlisted public Teable website links while keeping noopener.
• Serve a noindex root language selector so campaign parameters survive the localized redirect.
• Add explicit Help outbound click events and query-free source-document markers for matching website arrivals. Preserve existing UTMs and fragments; no new page_view/config calls.

Verification

• Three independent fix commits.
• 26 Node regression tests passed; source SEO checks passed for 1,885 current and 29 archive pages; Mintlify validate passed.
• Running Mintlify preview on port 3003: root, index, legacy language route and localized route return 200; custom scripts are included and served byte-identically.
• Independent agent review passed with no actionable findings; Help and website protocols match for all 27 audited links and 363 catalog/locale pairs.

Deployment boundaries

• This PR does not include pending metadata PR Improve Help page titles and descriptions across 11 languages #281.
• The existing help.teable.cn root 301 is emitted by an external gateway; the user explicitly deferred gateway changes. Use /zh or a direct document URL for campaigns.
• Both GA4 properties still need source_path, target_path, source_domain, link_category and locale event custom dimensions. The connected Admin write tool returns Insufficient scope after reauthorization; readback confirms none were added.
• No synthetic events sent to production. New event receipt and final campaign attribution require production deployment and GA processing.

Companion website arrival PR: https://github.com/teableio/teable-official/pull/334