chore(release): prepare 1.0.3 stable release

[wgqqqqq]

Summary

• Bump all stable desktop release metadata to 1.0.3.
• Synchronize Cargo.lock and the release-please manifest.
• Add the 1.0.3 updater release note so users see it after checking for updates:

  系统优化 AI 对话界面与整体性能，让对话更清晰、交互更流畅。

• Pass versioned release notes into the generated latest-v1.json updater manifest.

Validation

• pnpm run release:version:check
• pnpm run test:release-packaging
• node --test scripts/relay/package-contract.test.mjs
• pnpm run check:github-config
• pnpm run check:repo-hygiene
• git diff --check