docs: date leaderboard results and attach Astra retest evidence

[ye1457]

Summary

• Add one shared September 2026 evaluation notice in English/Chinese to the bottom-left footer, directly above RPent Leaderboard, in Performance and Time & Token Costs. Remove it from the page header and place it below the charts in all four overview images; standalone/offline/native fallback stay synchronized.
• Preserve all 181 performance records, 11 cost records, methods, sorting and CSV contracts; external baselines are not covered by the date notice.
• Include sanitized single-task OpenDrawer logs (seeds 1-5 in both periods) for the Astra retest issue. Preserve success outcomes and token counts; remove private paths/addresses and include source-attempt selection and checksums. Do not publish the full comparison archive.

Companion documentation: RLinf/RPent#261

Retest report and evidence: RLinf/RPent#260

Validation

• Strict English/Chinese documentation builds passed (126 pages).
• All 543 shared-date/data/CSV checks passed, including exact footer positioning, light/dark desktop/mobile, default collapse, native fallback and interactions.
• 103 browser screenshots re-captured for local review, including all 19 performance views, three cost groups, six footer captures and bilingual retest issue previews.
• Single-task ZIP: 10 result records verified, 69 files, 181,902 bytes; private-string scan passed.
• ZIP SHA-256: b7690d7b2570c3fa203128ab0abd6964041b9697a604126ca7d00d548ccd1777.
• 27 immutable CDN/Raw checks passed, including standalone assets and the public single-task ZIP; responses match local files byte for byte.

The Chinese preview has been accepted. Marked Ready for review at the user's request; not merged.