Sync main history into staging

[suguanYang]

Summary

• Merge main history into staging so future staging -> main release PRs do not hit duplicated-history conflicts.
• Resolve the duplicated-history conflicts by keeping the current staging file tree unchanged.
• This PR is intentionally a history-sync PR, not a functional code change.

Verification

• origin/main is an ancestor of this branch.
• origin/staging is an ancestor of this branch.
• git diff --name-status HEAD origin/staging is empty, confirming the tracked file tree matches current staging.
• git diff --check --cached passed before the sync merge commit.