packages: add starship; swap swww for awww

starship is required by fish/config.fish (starship init fish | source)
but was missing — fresh installs would have a broken shell prompt.

swww was listed but the actually-installed wallpaper daemon is awww
(matching the niri/config.kdl change in the previous commit).

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

packages.txt

@@ -3,7 +3,7 @@ waybar
 wofi
 mako
 alacritty
-swww
+awww
 grim
 slurp
 swappy
@@ -38,3 +38,4 @@ xwayland-satellite
 power-profiles-daemon
 fw-fanctrl
 satty
+starship