[ui/core] Add a menu to increment file version

[Alxiice]

Description of the PR

Increments the version of the file and save

Note

Here are the rules to increment the version :

• scene.mg -> scene1.mg
• scene1.mg -> scene2.mg
• scene1.mg and scene2.mg exists -> scene3.

• Add a "Save new version" button in the file menu
• The shortcut is Ctrl+Alt+S

Review requested

• You can try to break the regex '^(.+?)(\d+)$' that is supposed to catch the name (sceneN.mg)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.74%. Comparing base (da30eaf) to head (911f199).
⚠️ Report is 3 commits behind head on develop.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2980      +/-   ##
===========================================
+ Coverage    79.61%   79.74%   +0.12%     
===========================================
  Files           64       64              
  Lines         8595     8648      +53     
===========================================
+ Hits          6843     6896      +53     
  Misses        1752     1752              

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[Copilot]

Pull request overview

This PR adds a "Save New Version" feature that automatically increments the version number in the filename when saving. The implementation adds a new menu item with a keyboard shortcut (Ctrl+Alt+S) that generates the next available version number (e.g., scene.mg → scene1.mg → scene2.mg).

Changes:

• Added UI action in the File menu for "Save New Version" with Ctrl+Alt+S shortcut
• Implemented version incrementing logic using regex pattern matching
• Integrated the feature through UI and core graph layers

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
meshroom/ui/qml/Application.qml	Adds "Save New Version" action to File menu with keyboard shortcut and proper enable conditions
meshroom/ui/graph.py	Adds UI layer wrapper for saveAsNewVersion that delegates to core and manages undo stack
meshroom/core/graph.py	Implements core logic for version path generation and saving to new version

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