Add Mona Slice badge app

badge/apps/mona_slice/README.md

@@ -0,0 +1,11 @@
+# Mona Slice
+
+Claim cozy corners by carving the playfield while keeping Mona and her friends safe.
+
+## Usage
+
+Move the cursor with the arrows, press Select to start a cut, and press Back to switch between horizontal and vertical cuts; the slicer marker shows the selected direction. The cursor can move anywhere, and a cut started in claimed territory travels through it into open space; once in open space, each end stops independently at the next wall, claimed area, or edge. Claim at least 75% of the field before losing all three paws. Mona's animated sprite always faces left or right, following her horizontal movement. Clear a level to meet more Monas, up to five, and face faster movement. Press Select to begin, continue, or replay. No extra hardware or network access is required.
+
+## Credits
+
+Mona sprite sheet and icon are reused from this repository's `flappy_mona` app; `assets/mona_left.png` is a horizontally mirrored copy.