feat(home): add satty for screenshot annotation

Added satty (Wayland-native screenshot annotation tool) and integrated it with the Capture flow.
Wired `$mod SHIFT, Print` to slurp a region and open satty.
Added "Annotate region" to the rofi Capture menu (Tools > Capture).
Added satty's configuration via home-manager to inject the active theme's palette colors into its UI.

Verified: V1 (flake check --no-build, home activation package build).
Pending: V3 hardware/visual check for the satty UI (queued in HARDWARE-QUEUE.md).

modules/home/default.nix

@@ -27,6 +27,7 @@
     ./mime.nix      # default applications (mimeapps.list), degrades with the suite
     ./recording.nix # nomarchy-record: screen recording behind Capture + the bar ⏺
     ./battery-notify.nix # low-battery toasts at the bar's 25/10% thresholds
+    ./satty.nix     # satty screenshot annotation tool, themed
   ];
 
   # Clipboard history (wl-paste watcher); browsed via the SUPER+CTRL+V