Adds a spinner when performing a lazy install

[arcanis]

Most Yarn commands now silently run installs under the hood when they detect the project isn't in sync compared to the last modification time of package.json. Only problem is that it's a little too silent and it may look like the command is unexpectedly hanging.

To address this we now display a spinner if the install takes more than 200ms.

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Note

Medium Risk
Touches the async lazy-install control flow with a new tokio::select! timing branch and threaded terminal output, which could affect install completion timing or terminal behavior in edge cases.

Overview
Improves UX for lazy_install by showing a spinner message ("Installing dependencies...") only when running in a TTY and the install hasn’t finished within ~200ms; non-terminal contexts still run silently.

Refactors lazy_install to pin the install future, race it against a short sleep via tokio::select!, start/stop a start_progress spinner around the remaining work, and updates the progress thread to flush immediately after hiding the cursor to make terminal state changes visible promptly.

^{Reviewed by Cursor Bugbot for commit 328144f. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

⏱️ Benchmark Results

gatsby install-full-cold

Metric	Base	Head	Difference
Mean	2.420s	2.405s	-0.62% ✅
Median	2.422s	2.407s	-0.65% ✅
Min	2.386s	2.360s
Max	2.447s	2.444s
Std Dev	0.013s	0.016s

📊 Raw benchmark data (gatsby install-full-cold)

Base times: 2.415s, 2.433s, 2.420s, 2.439s, 2.411s, 2.424s, 2.433s, 2.424s, 2.432s, 2.436s, 2.424s, 2.447s, 2.425s, 2.429s, 2.411s, 2.410s, 2.416s, 2.426s, 2.427s, 2.405s, 2.394s, 2.416s, 2.421s, 2.413s, 2.419s, 2.412s, 2.427s, 2.404s, 2.425s, 2.386s

Head times: 2.412s, 2.399s, 2.394s, 2.394s, 2.396s, 2.417s, 2.405s, 2.408s, 2.383s, 2.360s, 2.403s, 2.397s, 2.391s, 2.380s, 2.394s, 2.402s, 2.410s, 2.414s, 2.444s, 2.399s, 2.414s, 2.414s, 2.408s, 2.417s, 2.413s, 2.421s, 2.426s, 2.420s, 2.415s, 2.399s

---

gatsby install-cache-and-lock (warm, with lockfile)

Metric	Base	Head	Difference
Mean	0.355s	0.351s	-1.02% ✅
Median	0.353s	0.351s	-0.51% ✅
Min	0.345s	0.344s
Max	0.385s	0.369s
Std Dev	0.010s	0.004s

📊 Raw benchmark data (gatsby install-cache-and-lock (warm, with lockfile))

Base times: 0.353s, 0.348s, 0.350s, 0.352s, 0.349s, 0.352s, 0.352s, 0.352s, 0.349s, 0.352s, 0.355s, 0.353s, 0.355s, 0.356s, 0.355s, 0.357s, 0.350s, 0.357s, 0.354s, 0.355s, 0.384s, 0.345s, 0.350s, 0.346s, 0.347s, 0.385s, 0.376s, 0.355s, 0.364s, 0.345s

Head times: 0.349s, 0.350s, 0.350s, 0.352s, 0.348s, 0.348s, 0.358s, 0.344s, 0.352s, 0.355s, 0.351s, 0.351s, 0.347s, 0.349s, 0.348s, 0.348s, 0.350s, 0.350s, 0.351s, 0.348s, 0.351s, 0.369s, 0.353s, 0.356s, 0.353s, 0.354s, 0.351s, 0.354s, 0.352s, 0.353s

[arcanis]

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[cursor]

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^{Reviewed by Cursor Bugbot for commit 328144f. Configure here.}