27.1.0.0

• [*] [internal] Experimental Gutenberg editor: add Lockdown Mode detection [#25776]
• [*] [internal] In-app updates: guard the flexible update notice against double-posting when two update checks race [#25666]
• [*] [build tooling] Add a String Catalog localization pipeline (plurals + build-free catalog generation) with a CI coverage gate [#25688]
• [*] Fix categories and tags not working on self-hosted sites with XML-RPC disabled [#25767]
• [*] Fix Blogging Reminders text color in dark mode [#25780]
• [*] Share extensions: Fix the site picker showing an error while sites are still loading [#25798]
• [*] Share Extension: Fix a crash after uploading a post to WordPress.com [#25773]