Make the rice shareable: appearance-only default, --with-shell, --layouts, --restore, 07-input and 99-personal split

- default install: SwayFX + DMS + kitty + fonts/theme + hotkeys/screenshots only
- zsh/tmux/CLI tools behind --with-shell; personal apps/autostart/mouse speed removed from the repo
- keyboard layouts prompt/--layouts, user-editable files (07-input.conf, dms/settings.json) never overwritten
- --restore (oldest backup), unique backup dirs, README rewritten for strangers, private URL removed

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

examples/99-personal.conf.example

@@ -0,0 +1,12 @@
+# Copy to ~/.config/sway/config.d/99-personal.conf. install.sh never touches 99-*.conf files.
+
+# Mouse / touchpad speed (-1 slowest .. 1 fastest)
+input type:pointer {
+    pointer_accel -0.5
+}
+input type:touchpad {
+    pointer_accel 0.3
+}
+
+# Autostart apps (xdg-autostart does not run under sway)
+# exec sh -c 'sleep 5; command -v nextcloud >/dev/null && nextcloud --background'