[ui] Implement status bar to display messages

[Alxiice]

Description

• Add a StatusBar QML element to display messages
  • Consists of a text message and an icon
  • a showMessage(message, status, duration) funciton is used to change the icon/text for a specific duration (5 seconds by default)
  • 4 status : default, ok, warning, error
    
• integrate this StatusBar on Meshroom footer ToolBar
• Add slots to be able to send the messages for the python side
• Add slots and signals on reconstruciton to make sure the UI is not blocked when plugins are reloaded

Example

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.08%. Comparing base (c2f3115) to head (fe4fe0c).
⚠️ Report is 18 commits behind head on develop.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2861   +/-   ##
========================================
  Coverage    79.08%   79.08%           
========================================
  Files           51       51           
  Lines         6889     6889           
========================================
  Hits          5448     5448           
  Misses        1441     1441           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Copilot]

Pull Request Overview

This PR implements a status bar component for the Meshroom UI to display informational messages with different status levels (default, ok, warning, error). The status bar appears in the bottom toolbar and provides visual feedback for operations like plugin reloading.

Key changes:

• Create a new StatusBar QML component with message display and status icons
• Integrate the status bar into the main application footer
• Add Python-side message handling through the app interface
• Implement asynchronous plugin reloading with status notifications

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
meshroom/ui/qml/Controls/StatusBar.qml	New status bar component with message display and timer functionality
meshroom/ui/qml/Controls/qmldir	Register the new StatusBar component
meshroom/ui/qml/Application.qml	Integrate status bar into footer and update plugin reload action
meshroom/ui/app.py	Add showMessage method and forceUIUpdate for Python-side message handling
meshroom/ui/reconstruction.py	Implement asynchronous plugin reloading with status notifications
meshroom/core/node.py	Minor whitespace addition

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}