screenshot: revert flameshot, use grim+slurp+satty pipeline

Flameshot's portal-based capture path on niri triggers an
xdg-desktop-portal access prompt on every invocation, blocking
the screenshot itself. grim talks to wlr-screencopy directly and
never touches the portal, so no prompt.

Pipeline: slurp (region) → grim (capture) → satty (annotate +
copy + save). satty replaces the wofi action menu by being the
post-capture surface itself.

- scripts/screenshot.sh added
- install.sh symlinks it; flameshot.ini generator removed
- niri Mod+Print → "screenshot"
- packages.txt drops flameshot
- docs tables updated

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

install.sh

@@ -40,19 +40,6 @@ default-timeout=4000
 """
 open(os.path.expanduser("~/.config/mako/config"), "w").write(config)
 PYEOF
-mkdir -p ~/.config/flameshot
-if [ ! -f ~/.config/flameshot/flameshot.ini ]; then
-    cat > ~/.config/flameshot/flameshot.ini <<'INI'
-[General]
-disabledTrayIcon=true
-showStartupLaunchMessage=false
-showHelp=false
-copyAndCloseAfterUpload=true
-uiColor=#81a2be
-contrastUiColor=#1d1f21
-contrastOpacity=190
-INI
-fi
 ln -sf "$(pwd)/gtklock/config.ini" ~/.config/gtklock/config
 ln -sf "$(pwd)/gtklock/style.css" ~/.config/gtklock/style.css
 ln -sf "$(pwd)/fish/config.fish" ~/.config/fish/config.fish
@@ -71,6 +58,7 @@ ln -sf "$(pwd)/scripts/clipboard.sh" ~/.local/bin/clipboard-picker
 ln -sf "$(pwd)/scripts/power-profile.sh" ~/.local/bin/power-profile
 ln -sf "$(pwd)/scripts/fan-profile.sh" ~/.local/bin/fan-profile
 ln -sf "$(pwd)/scripts/waybar-restart.sh" ~/.local/bin/waybar-restart
+ln -sf "$(pwd)/scripts/screenshot.sh" ~/.local/bin/screenshot
 
 echo "==> Enabling systemd user services"
 mkdir -p ~/.config/systemd/user