Nginx UI 2.8.4

Features
- Show which sites and streams use each certificate by @0xJacky (b8a0895a)
- Add a retention count to auto backup tasks by @SulimanAbdulrazzaq (6a079e01)
- Add Italian (it_IT) translation by @BluLupo (1c72533e)
- Tidy the certificate editor header and actions by @0xJacky (70147328)
Bug Fixes
- Isolate session cookies by protocol by @0xJacky (881ef81c)
- Keep certificates with long identifier lists in their own directory by @0xJacky (035192b8)
- Migrate shared certificates and wait for renewal before sending expiry notices by @0xJacky (f3a368d2)
- Skip backup retention cleanup when another task shares the same file names by @0xJacky (e95a6e66)
- Limit the height of the add-site config template and scroll inside it by @akinoccc (4e95c83b)
Contributors
@0xJacky @SulimanAbdulrazzaq @BluLupo @akinoccc

Features
- Add a Snippets page to manage reusable Nginx snippets: edit them on their own page with variables and a live preview, start from built-in templates, include them from the site editor, and sync them to nodes by @Hintay (dd7a40a7, d4bb80f6, f711f7b0, 2a9fb2cd)
- Pick a config template when creating a site by @akinoccc (dde9c05a)
- Set a custom URL that a dashboard site card opens when clicked by @EFX1SZH (bb7d07a6)
Bug Fixes
- Fix "database is locked" errors across the app after upgrading to v2.8.x, caused by the site check auto-upgrade waiting on its own SQLite transaction (#1994) by @0xJacky (f7ab4d9a)
- Stop access list saves from holding the database lock while Nginx tests and reloads by @0xJacky (b2cb7530)
- Replicate certificates to the nodes that serve them, so synced sites no longer fail with "cannot load certificate" and renewals reach those nodes by @0xJacky (06c8f951)
- Complete the Korean translation and fill in missing translations for the other languages by @0xJacky (933a8560, ce183d87)
Contributors
@0xJacky
@Hintay
@akinoccc
@EFX1SZH

Features
- None.
Bug Fixes
- Complete missing translations for the new access list, upstream group and certificate texts across all languages by @0xJacky (e6d755bd)
Contributors
@0xJacky