Feat(ci): Add stale bot

[hoangdv2429]

PR Standards

This PR add stale bot CI to automatically mark PR as stale after 8 days and close PR after 11 days without activity. Except PR with "security, proposal, blocked, dym-internal" labels.

Another CI workflow will check opened, synchronize PR and mark those PR as dym-internal to exclude it from being mark and close.

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For Author:

• Targeted PR against correct branch
• included the correct type prefix in the PR title
• Linked to Github issue with discussion and accepted design
• Targets only one github issue
• Wrote unit and integration tests
• All CI checks have passed
• Added relevant godoc comments

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For Reviewer:

• confirmed the correct type prefix in the PR title
• Reviewers assigned
• confirmed all author checklist items have been addressed

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After reviewer approval:

• In case targets main branch, PR should be squashed and merged.
• In case PR targets a release branch, PR should be rebased.

[danwt]

nice