release: publish Web Office in a3s 0.9.9

[ZhiXiao-Lin]

Summary

• pin the immutable A3S root commit containing the unified Work office workspace
• bundle the published A3S WebView 0.1.5 helper and align Code Core 6.3.0 plus Use Extension 0.1.3 release prerequisites
• replace the stale missing release-manifest copy with the canonical published-crate lock generation path
• finalize the 0.9.9 changelog date and native Agent Island release notes

Validation

• bash .github/scripts/test-check-release-state.sh
• bash .github/scripts/check-release-state.sh 0.9.9 6.3.0 0.1.13 2.0.0
• release workflow YAML parse
• verified the exact root Web commit and public WebView 0.1.5 release
• verified all nine required A3S crate versions on crates.io
• isolated published-dependency cargo metadata --locked
• isolated cargo package --locked --allow-dirty; a3s 0.9.9 compiled successfully
• origin/main CI run 29882416745 passed