fix(staking): use the sdk to drive epoch timestamps

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Name	Status	Preview	Comments	Updated (UTC)
api-reference	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 11, 2024 7:56pm
staking-v2	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 11, 2024 7:56pm

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| Name | Status | Preview | Comments | Updated (UTC) | | :--- | :----- | :------ | :------- | :------ | | **xc-admin-frontend** | ⬜️ Ignored ([Inspect](https://vercel.com/pyth-web/xc-admin-frontend/FJu2RAv3pcwWefUofrWBKBvhRLF6)) | [Visit Preview](https://xc-admin-frontend-git-fork-cprussin-use-staking-99b15a-pyth-web.vercel.app) | | Sep 11, 2024 7:56pm |