feat(dashboard): add statistics API and enhance homepage dashboard cards * feature/20251219_yjp: (2 commits) feat(index): add homepage with dashboard cards and knowledge graph support feat(dashboard): add statistics API and enhance homepage dashboard cards Signed-off-by: vrhs@163.com <accounts_660b6454a0eb398d3f8d2c76@mail.teambition.com> Merged-by: vrhs@163.com <accounts_660b6454a0eb398d3f8d2c76@mail.teambition.com> CR-link: https://codeup.aliyun.com/redbearai/python/redbear-mem-open/change/109