Improved peek and UI enhancements

Improved peek Peek is one the semi-secrets of the Linear UI. It’s a quick way to glance over the focused issue in issue lists similar to Quicklook in macOS. It can be useful in cases where you are trying prioritize several issues in a list, find one particular issue, or decide what to do with an issue. It's a great feature, so it deserves a more prominent key to invoke it. We've remapped the key from Alt to Space. Peek is active while you hold down Space, or you can quickly press Space once to toggle it on, and once more to toggle it off. File uploads Linear already supported photo and video uploads, and now we added generic support for all files type. You can add any file to the issue description or a comment as attachments. To attach a file, simply drag and drop files from your computer to the description editor or comment box. Add more favorites In addition to projects, you can now favorite individual issues or cycles and have them appear in the sidebar for quick access. Other improvements and fixes: The associated projects in issue lists now link to the project Improved hover states for many components Prevents background auto-update when you're in the middle of editing an issue Fixed an exception in billings page when you have an active subscription Fixed subscribers button with several subscribers Issue title now renders in correct color in Safari Further search improvements for better matching