restructure

- users/rin/default.nix -> users/rin.nix
- users/rin/home.nix +-> users/rin.nix
- users/rin/*.nix -> modules/user/*.nix
- users/rin/scripts/ -> scripts/
- hosts/winter/default.nix -> hosts/winter.nix
- hosts/winter/*.nix -> modules/system/*.nix

- modules are dynamically imported as sets for system and user

modules/user/picom.nix

@@ -0,0 +1,43 @@
+{ config, ... }: {
+  services.picom = {
+    enable = true;
+    experimentalBackends = true;
+
+    blur = true;
+    blurExclude = [
+      (builtins.concatStringsSep " && " [
+        "class_g != 'Alacritty'"
+        "class_g != 'kitty'"
+        #"class_g != 'Polybar'"
+        "class_g != 'URxvt'"
+      ])
+    ];
+    fade = true;
+    fadeDelta = 5;
+    fadeSteps = [ "0.05" "0.05" ];
+
+    opacityRule = [
+      "80:class_g = 'Alacritty' && !focused"
+      "95:class_g = 'kitty' && !focused"
+    ];
+    vSync = true;
+
+    extraOptions = ''
+      glx-no-stencil = true;
+      glx-copy-from-front = false;
+      glx-no-rebind-pixmap = true;
+      use-damage = true;
+
+      blur-method = "dual_kawase";
+      blur-strength = 15;
+
+      detect-transient = true;
+      detect-client-leader = true;
+      detect-client-opacity = true;
+      detect-rounded-corners = true;
+      use-ewmh-active-win = true;
+      mark-wmwin-focused = true;
+      mark-ovredir-focused = true;
+    '';
+  };
+}