Update Qt

[jimporter]

Spinning this off from the update to C++20 to nail down some strange behavior on macOS.

[codecov]

Codecov Report

❌ Patch coverage is 81.57895% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.43%. Comparing base (4980c78) to head (323c490).
⚠️ Report is 190 commits behind head on main.

Files with missing lines	Patch %	Lines
...rc/platform/backends/qemu/linux/dnsmasq_server.cpp	40.00%	3 Missing ⚠️
src/network/url_downloader.cpp	33.33%	2 Missing ⚠️
src/utils/utils.cpp	92.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4390      +/-   ##
==========================================
+ Coverage   88.97%   89.43%   +0.45%     
==========================================
  Files         238      240       +2     
  Lines       15253    13851    -1402     
==========================================
- Hits        13572    12387    -1185     
+ Misses       1681     1464     -217     

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[jimporter]

• Passing job with just the first commit (which improves failing test output)
• Failing job with Qt upgrade

[jimporter]

❌ Patch coverage is 96.15385% with 1 line in your changes missing coverage. Please review.

This is a strange coverage report...

[sharder996]

How do you feel about moving to Qt 6.10 right away? Or, was there a specific reason for using 6.9?

[jimporter]

How do you feel about moving to Qt 6.10 right away? Or, was there a specific reason for using 6.9?

I'm not strongly opposed, though Ubuntu 25.10 uses Qt 6.9.2, so sticking with the 6.9 series on Mac and Windows would mean less version skew on our official builds (once we start using 25.10 in CI anyway e: GitHub uses LTS images). If we don't think that matters though, we can switch to 6.10.

[xmkg]

How do you feel about moving to Qt 6.10 right away? Or, was there a specific reason for using 6.9?

I'm not strongly opposed, though Ubuntu 25.10 uses Qt 6.9.2, so sticking with the 6.9 series on Mac and Windows would mean less version skew on our official builds (once we start using 25.10 in CI anyway e: GitHub uses LTS images). If we don't think that matters though, we can switch to 6.10.

FTR I plan to migrate the QT to vcpkg too after this one lands, so feel free to use the latest and the greatest.

[jimporter]

Note: The directory structure for the qtbase binary archive is different now.