Initial commit: Chatter — assistive-writing app for reMarkable Paper Pro Move

Direct-framebuffer ink pipeline (stock-quality strokes), finger-wipe erase,
growable scrolling canvas with color-ghost cleanup, bidirectional toggle with a
persistent 4-finger return launcher, instant button feedback. Includes prebuilt
aarch64 binaries (dist/), build/deploy/install scripts, a user guide, and a
complete technical reference.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/chatter-launcher.service

@@ -0,0 +1,13 @@
+[Unit]
+Description=Chatter launcher (multi-finger gesture watcher)
+After=home.mount data.mount multi-user.target
+# Binary + scripts live on the persistent /home volume.
+RequiresMountsFor=/home/root/chatter
+
+[Service]
+ExecStart=/home/root/chatter/chatter-launcher
+Restart=always
+RestartSec=2
+
+[Install]
+WantedBy=multi-user.target