Move the search result counter (e.g. "1/30") inside the search text
field using an overlay, preventing layout shift when results appear.
This PR was authored with Claude Code.
There is a sparkle-related 'issue' with the previous implementation. When you download/install in the `updateAvailable` state, if you don't install it, then check the updates again. Sparkle loses its downloaded stage in the delegate (it's normal when I use the sparkle source code). This time, when you click install in the `updateAvailable` state, it just uses the previous downloaded package and starts to install, without calling `showReady(toInstallAndRelaunch:)`.
I think removing `readyToInstall` in our customed ui, will reduce one step to install an update for most of the users out there, which makes sense, since the current package is pretty small, only takes a few seconds to download for a normal network, and they intended to install this update.
Resolves Issue #8357
### Implementation
Following the existing `onResize` callback pattern in
`TerminalSplitTreeView`, I added an `onEqualize` callback to
`SplitView`. When a divider is double-tapped, the callback retrieves a
surface from that `TerminalView`'s `SplitTree` and calls `splitEqualize`
to equalize the entire tree.
### Context
There is an existing PR #8364 that implements this feature but uses
`focusedSurface`, which doesn't work for unfocused windows. Since that
PR has been inactive for a few months after requested changes, I've
implemented this alternative approach.
Credit to @liby for that initial implementation!
### AI Usage
I chatted with Claude Code in Plan mode to understand the relationship
between surfaces and the split tree/split views, but I wrote all the
code myself.
### Screenshot
https://github.com/user-attachments/assets/0efd70ef-c90e-4b50-b853-b05e2ca2be67
