Add project start screen

[alex-ur88]

Summary

Adds a project start screen for the empty/no-images-loaded state so users have clear first actions when launching the tool.

Changes

• Adds a centered start screen with Open Project and Open Image Folder actions
• Shows recent project and recent image folder shortcuts after those paths have been used
• Stores recent shortcuts locally with QSettings
• Hides the start screen once an image dataset is loaded and restores it when the dataset is cleared
• Applies Ruff cleanup needed because CI runs pre-commit across all files
• Stabilizes viewport action toggle tests that were already failing on clean upstream/staging

Notes

• This PR only covers the project start screen slice from the earlier combined workflow PR
• Recent shortcuts are local app convenience state, not .annoproj project state
• The viewport test fix is included because the same failures reproduced on clean upstream/staging, not because the start screen introduced them

Testing

• python -m pytest src/tests/integration/test_viewport_actions.py -q
• python -m ruff check src/tests/integration/test_viewport_actions.py
• python -m ruff format --check src/tests/integration/test_viewport_actions.py
• CI checks passed

[MikeSzklarz]

If you could just comment here what files are changed.

For the future commits dont do the ruff pre commit even if it fails. We will remove the ruff stuff as its causing issues for checking whats changed in PR's. For example it says 17 files changes even though it was probably only a couple.

You dont need to change anything now, just lmk which files were changed for the actual implementation

[alex-ur88]

If you could just comment here what files are changed.

For the future commits dont do the ruff pre commit even if it fails. We will remove the ruff stuff as its causing issues for checking whats changed in PR's. For example it says 17 files changes even though it was probably only a couple.

You dont need to change anything now, just lmk which files were changed for the actual implementation

Yeah absolutely. The actual project start screen implementation changed the following files:

• src/views/annomate/window.py
• src/views/app_window.py

Separately, I also changed 'src/tests/integration/test_viewport_actions.py' for the small test stabilization fix around the image-viewer grid/center-crop toggle tests. The remaining changed files are from the Ruff/pre-commit cleanup stuff.

Understood on the Ruff/pre-commit point. For future PRs, I won’t apply Ruff cleanup just to get the check passing from now on.