- Selection/focus improvements (reduces flickers, move selection more
correctly throughout the list)
- Adds open folder button in the sidebar header
- Fixes sidebar header design, including the thread view one, too
- Fixes behavior of cmd-n when focused in the sidebar
- Changes the design for the "new thread" button in the sidebar and adds
a preview of the prompt on it
- Rename items in the "start thread in" dropdown

Release Notes:

- N/A

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Co-authored-by: cameron <cameron.studdstreet@gmail.com>