[docs] Add Apache Doris 4.1.3 release info

[morningman]

Summary

• Publish Apache Doris 4.1.3 as Latest in the quick-download and all-releases data, using source filename version 4.1.3-rc02.
• Add synchronized English and Chinese release notes, Core index entries, and sidebar navigation; restore the missing 4.1.2 entry in ALL_VERSIONS.
• Improve the add-release skill with Core index routing, RC-aware artifact handling, bilingual and version-drift checks, validation tiers, and a reusable validator with regression tests.

Validation

• node --test doc-tools/skills/add-release/scripts/validate-release.test.mjs (4/4 passed)
• node doc-tools/skills/add-release/scripts/validate-release.mjs --component doris-core --version 4.1.3 --series 4.1 --source-version 4.1.3-rc02 --release-date 2026-07-13 --position latest --source-dir https://dist.apache.org/repos/dist/release/doris/4.1/4.1.3/ (70 checks passed, including all 12 artifact URLs)
• Skill structure validation passed with skill-creator quick_validate.py
• sidebarsReleases.json JSON parse check
• git diff --check

Build

• yarn typecheck and yarn build were not run per request.