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/satty.nix

@@ -0,0 +1,31 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.nomarchy;
+  t = cfg.theme;
+  c = t.colors;
+in
+{
+  config = lib.mkIf (pkgs.lib.meta.availableOn pkgs.stdenv.hostPlatform pkgs.satty) {
+    home.packages = [ pkgs.satty ];
+
+    xdg.configFile."satty/config.toml".text = ''
+      [general]
+      # Set the default tool to pointer or arrow?
+      initial-tool = "arrow"
+      copy-command = "wl-copy"
+      # Hitting copy also saves? Let the user hit save if they want to save.
+      # save-after-copy = false
+
+      [color-palette]
+      palette = [
+        "${c.accent}ff",
+        "${c.bad}ff",
+        "${c.warn}ff",
+        "${c.good}ff",
+        "${c.text}ff",
+        "${c.base}ff"
+      ]
+    '';
+  };
+}