chore(release): bump version to 0.31.0

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packaging/release-notes.md.tmpl

@@ -3,6 +3,7 @@
 Notebook app for pen, touch and mouse on Linux (tested on Zorin OS 18 / Ubuntu 24.04).
 
 ### Highlights:
+- **View only**: 👁 in the toolbar hides the tools – pen, finger and mouse only scroll and zoom (the pen glides on like a finger), nothing can be changed by accident; tap 👁 again to write
 - **Text box fix**: Ctrl+Plus/Minus now only zooms the page, no longer the whole interface as well – that made text jump to another place when leaving a text box
 - **Writing fixes**: A snapped highlighter keeps its width; tips (e.g. of a "1" or of exponents) are drawn round instead of cut off, and the stroke no longer jumps when the pen lifts. Finger swipes glide more reliably
 - **Faster scrolling**: A quick finger swipe keeps gliding; in the continuous view a scrollbar (opposite the toolbar, with the page number while dragging) jumps through long notebooks and PDFs; the mouse wheel scrolls twice as far. New notebooks are continuous; fixed pages are still available in the ☰ menu