fix vector digitizing truncating geometry precision decimals

[ViperMiniQ]

#58351

Digitizing box still uses the same QLocale to show values, but instead of the default precision of 6, it now has a precision of 15. After 4 decimals, it changes to scientific notation, depending on the user set locale settings.
As the same object is used to convert values to and from, scientific notation is a valid representation, both for showing the actual values and for saving.

[nirvn]

There's an OK which should never have been there to begin with :) when that's fixed, we can merge.

[github-actions]

🪟 Windows builds ready!

Windows builds of this PR are available for testing here. Debug symbols for this build are available here.

(Built from commit 1be4c2a)

[github-actions]

The QGIS project highly values your contribution and would love to see this work merged! Unfortunately this PR has not had any activity in the last 14 days and is being automatically marked as "stale". If you think this pull request should be merged, please check

• that all unit tests are passing

• that all comments by reviewers have been addressed

• that there is enough information for reviewers, in particular

  • link to any issues which this pull request fixes

  • add a description of workflows which this pull request fixes

  • add screenshots if applicable

• that you have written unit tests where possible
  In case you should have any uncertainty, please leave a comment and we will be happy to help you proceed with this pull request.
  If there is no further activity on this pull request, it will be closed in a week.