Add Transcode entry to Nautilus context menu (#5635)

* Add Transcode entry to Nautilus context menu

Right-click on image or video files in Nautilus to send them to
omarchy-transcode in a presentation terminal, mirroring the existing
LocalSend integration.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* Use shlex.quote for shell-safe command construction in transcode.py

Quote both the resolved binary path and file paths via shlex.quote
instead of a custom escaper. Addresses Copilot review on #5635.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* Style changes

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: David Heinemeier Hansson <david@hey.com>

migrations/1778099894.sh

@@ -0,0 +1,3 @@
+echo "Add Transcode entry to Nautilus context menu"
+
+source $OMARCHY_PATH/install/config/nautilus-python.sh