feat: replace swayidle with hypridle for idle management

hypridle pairs with hyprlock, honors idle inhibitors (video/calls no
longer blank or lock the screen), and is config-file driven. Same staging
as before: blank monitors @5m, lock @10m, suspend-then-hibernate @30m.
Locks via 'loginctl lock-session' so the before-sleep lock is deduplicated.

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

packages.txt

@@ -11,7 +11,7 @@ wl-clipboard
 brightnessctl
 pamixer
 hyprlock
-swayidle
+hypridle
 ttf-jetbrains-mono-nerd
 polkit-gnome
 fprintd