Ensure that we display an appropriate error message for when there is .maintenance file

[katinthehatsite]

Related issues

Fixes STU-1847

How AI was used in this PR

It was used to implement the solution.

Proposed Changes

This PR ensures that when there is a .maintenance file and a fresh lock, the appropriate message is displayed to the user if they try to stop and start the site. It detects the lock that is fresher than 10 minutes and after 10 minutes, WordPress will ignore the stale lock file.

Testing Instructions

• Pull the changes from this branch and start Studio with npm start
• Create a site (or use an existing one) and start it
• Test fresh lock — create a .maintenance file with a recent timestamp by running in your Terminal the following (make sure to replace with the name of your site):

  echo '<?php $upgrading = '$(date +%s)'; ?>' > ~/Studio/<your-site-name>/.maintenance

• Stop the site in Studio, then try to start it. You should see a message saying WordPress is in maintenance
  mode and the lock will expire within 10 minutes:

• Test no lock — delete the file:
  rm ~/Studio/<your-site-name>/.maintenance
• Start should work normally.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

[wpmobilebot]

📊 Performance Test Results

Comparing 63ad173 vs trunk

app-size

Metric	trunk	63ad173	Diff	Change
App Size (Mac)	1311.88 MB	1311.89 MB	+0.01 MB	⚪ 0.0%

site-editor

Metric	trunk	63ad173	Diff	Change
load	1065 ms	1036 ms	29 ms	⚪ 0.0%

site-startup

Metric	trunk	63ad173	Diff	Change
siteCreation	6501 ms	6477 ms	24 ms	⚪ 0.0%
siteStartup	6980 ms	6981 ms	+1 ms	⚪ 0.0%

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Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[katinthehatsite]

This is the behaviour compared to trunk: