Breakthrough Function Revolutionizes Storage Management with Expiry Calculation

New feature allows developers to easily derive expiry timestamps from block timestamps, enhancing efficiency in data management.

Commit Details:

feat: add new function to calculate storage unit expiry timestamp (#2645) ## Why is this change needed? Expose a function that calculates the expiry timestamp from just the block timestamp. ## Merge Checklist _Choose all relevant options below by adding an `x` now or at any time before submitting for review_ - [x] PR title adheres to the [conventional commits](https://www.conventionalcommits.org/en/v1.0.0/) standard - [x] PR has a [changeset](https://github.com/farcasterxyz/hub-monorepo/blob/main/CONTRIBUTING.md#35-adding-changesets) - [x] PR has been tagged with a change label(s) (i.e. documentation, feature, bugfix, or chore) - [ ] PR includes [documentation](https://github.com/farcasterxyz/hub-monorepo/blob/main/CONTRIBUTING.md#32-writing-docs) if necessary. <!-- start pr-codex --> --- ## PR-Codex overview This PR focuses on updating the `@farcaster/core` and `@farcaster/hub-nodejs` packages to version `0.18.6` and `0.15.6` respectively, along with introducing a new function for calculating storage unit expiry timestamps. ### Detailed summary - Updated `@farcaster/core` to version `0.18.6`. - Updated `@farcaster/hub-nodejs` to version `0.15.6`. - Added `getStorageExpiryTimestampFromBlockTimestamp` function in `limits.ts`. - Modified `getStorageUnitExpiry` to use the new expiry function. - Added tests for `getStorageExpiryTimestampFromBlockTimestamp` in `limits.test.ts`. > ✨ Ask PR-Codex anything about this PR by commenting with `/codex {your question}` <!-- end pr-codex -->