Fix sketcher mode handling to prevent unintended line creation during drag operations

Major changes:
- Fixed right-click handler to directly set mode to NONE instead of relying on main app signal handling
- Added safety checks in left-click handler to prevent drawing when no draggable point is found in NONE mode
- Enhanced mode compatibility by treating Python None as SketchMode.NONE in set_mode() method
- Added comprehensive debug logging for mode changes and interaction state tracking
- Resolved integration issue where persistent constraint modes were prematurely reset by main app
- Ensured point dragging is only enabled in NONE mode, preventing accidental polyline creation

This fixes the reported issue where deactivating the line tool would still create lines when dragging,
and ensures proper mode transitions between drawing tools and selection/drag mode.

main.app/Contents/MacOS/skimage/data/README.txt

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+This directory contains sample data from scikit-image.
+
+By default, it only contains a small subset of the entire dataset.
+
+The full detaset can be downloaded by using the following commands from
+a python console.
+
+  >>> from skimage.data import download_all
+  >>> download_all()

main.app/Contents/MacOS/skimage/io/_plugins/fits_plugin.ini

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+[fits]
+description = FITS image reading via PyFITS
+provides = imread, imread_collection

main.app/Contents/MacOS/skimage/io/_plugins/gdal_plugin.ini

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+[gdal]
+description = Image reading via the GDAL Library (www.gdal.org)
+provides = imread

main.app/Contents/MacOS/skimage/io/_plugins/imageio_plugin.ini

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+[imageio]
+description = Image reading via the ImageIO Library
+provides = imread, imsave

main.app/Contents/MacOS/skimage/io/_plugins/imread_plugin.ini

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+[imread]
+description = Image reading and writing via imread
+provides = imread, imsave

main.app/Contents/MacOS/skimage/io/_plugins/matplotlib_plugin.ini

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+[matplotlib]
+description = Display or save images using Matplotlib
+provides = imshow, imread, imshow_collection, _app_show

main.app/Contents/MacOS/skimage/io/_plugins/pil_plugin.ini

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+[pil]
+description = Image reading via the Python Imaging Library
+provides = imread, imsave

main.app/Contents/MacOS/skimage/io/_plugins/simpleitk_plugin.ini

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+[simpleitk]
+description = Image reading and writing via SimpleITK
+provides = imread, imsave

main.app/Contents/MacOS/skimage/io/_plugins/tifffile_plugin.ini

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+[tifffile]
+description = Load and save TIFF and TIFF-based images using tifffile.py
+provides = imread, imsave