feat: Add issue duplication agent using cache memory (#299)

* Initial plan

* feat: add issue duplication detector workflow with cache memory

Co-authored-by: Mossaka <5447827+Mossaka@users.noreply.github.com>

* docs: improve duplicate detection criteria and pagination guidance

Co-authored-by: Mossaka <5447827+Mossaka@users.noreply.github.com>

* feat: add bash tool with all commands allowed

Co-authored-by: Mossaka <5447827+Mossaka@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Mossaka <5447827+Mossaka@users.noreply.github.com>
Co-authored-by: Jiaxiao Zhou <duibao55328@gmail.com>

Author: Copilot