Add ability to start all stopped sites

[wojtekn]

Related issues

• Fixes STU-84

Proposed Changes

I propose to add an ability to start all stopped sites. I kept "Start all" only for case in which no sites are running, and "Stop all" for all other cases to keep UI simple.

Testing Instructions

1. Create 2+ sites in the app
2. Stop all sites — verify "Start all" button appears in sidebar
3. Click "Start all" — verify all sites start
4. Stop some sites — verify "Stop all" button is shown and "Start" is disabled

[wpmobilebot]

📊 Performance Test Results

Comparing e38caf7 vs trunk

site-editor

Metric	trunk	e38caf7	Diff	Change
load	2747.00 ms	2767.00 ms	+20.00 ms	🔴 0.7%

site-startup

Metric	trunk	e38caf7	Diff	Change
siteCreation	7080.00 ms	7085.00 ms	+5.00 ms	🔴 0.1%
siteStartup	3928.00 ms	3939.00 ms	+11.00 ms	🔴 0.3%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change

[gcsecsey]

Thanks for working on this @wojtekn, it's a very useful small enhancement. 🙌

The changes LGTM and when testing starting/stopping sites, it works well.

All sites stopped	Some sites stopped	All sites started

[gcsecsey]

This label was earlier only shown when any site was started, but now 0 sites running are shown by default. Maybe we could handle this case separately and show a No sites running label?

[wojtekn]

Makes sense, I changed it in e38caf7 so we will keep the current behavior. I will keep the opposite case as is, as it is a nice indicator of the number of all sites.

[sejas]

I confirm I'm able to start all the sites. The button is visible only if all the sites are stopped.
Code looks good. It iterates for each site and call startServer for each.
https://github.com/user-attachments/assets/64ac3441-0453-493c-9c91-4f5a3074081e

[bcotrim]

LGTM 👍
I wonder if we could add a studio site start --all similar to the existing studio site stop --all command, to keep CLI parity.
This discussion could be a follow up PR, if we decide to implement it, since the current change works perfectly already