feat: rewrite moonset in Rust (gtk4-rs + gtk4-layer-shell)

Feature-parity with Python v0.2.0. Same CSS, same UI, same actions.
Single 3.1 MB binary with embedded resources (CSS, wallpaper, avatar).

Modules: power.rs, i18n.rs, config.rs, users.rs, panel.rs, main.rs
45 unit tests passing. Python sources retained as reference.

resources/default-avatar.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="128" height="128" viewBox="0 0 512 512"><path fill="#PLACEHOLDER" d="M256 23c-16.076 0-32.375 3.73-48.178 10.24c-2.126 6.525-3.877 14.76-4.877 23.754c-1.31 11.79-1.73 24.706-1.87 36.819c33.864-3.704 75.986-3.704 109.85 0c-.14-12.113-.56-25.03-1.87-36.82c-1-8.992-2.75-17.228-4.877-23.753C288.375 26.73 272.076 23 256 23m100.564 19.332c9.315 7.054 18.107 14.878 26.282 23.234c1.53-6.65 4.69-12.696 9.03-17.695zm-170.03 1.49c-34.675 20.22-65.047 52.714-82.552 86.334c-33.08 63.536-39.69 156.956-.53 214.8C132.786 388.278 200.276 405 256 405s123.215-16.72 152.547-60.045c39.162-57.843 32.55-151.263-.53-214.8c-17.504-33.62-47.876-66.112-82.55-86.333c.578 3.65 1.057 7.388 1.478 11.184c1.522 13.694 1.912 28.197 2.014 41.267C347.664 99.427 362 104 368 110c32 32 75.537 134.695 16 224c-37.654 56.48-218.346 56.48-256 0c-59.537-89.305-16-192 16-224c6-6 20.335-10.573 39.04-13.727c.103-13.07.493-27.573 2.015-41.267c.42-3.796.9-7.534 1.478-11.184zM64 48c-8.837 0-16 7.163-16 16a16 16 0 0 0 7 13.227V145.5L73 132V77.21A16 16 0 0 0 80 64c0-8.837-7.163-16-16-16m358.81 3.68c-12.81 0-23 10.19-23 23s10.19 23 23 23s23-10.19 23-23s-10.19-23-23-23m25.272 55.205c-6.98 5.497-15.758 8.795-25.27 8.795c-.745 0-1.48-.027-2.214-.067a217 217 0 0 1 2.38 4.37l29.852 22.39zm-238.822 2.5c-17.257.09-37.256 3.757-53.233 16.12c-26.634 20.608-43.034 114.763-33.49 146.763c16.584-61.767 31.993-124.02 107.92-161.274a133.5 133.5 0 0 0-21.197-1.61zm-135.055 44.21L40.15 179.138l-14.48 72.408l38.18 45.814c-10.947-46.523-5.776-98.723 10.355-143.764zm363.59 0c16.13 45.042 21.302 97.242 10.355 143.764l38.18-45.815l-14.48-72.408zM106.645 375.93c-3.583 1.17-7.252 3.406-10.282 6.435c-4.136 4.136-6.68 9.43-7.164 14.104c.21.364.603 1.157 1.73 2.162c2.453 2.188 6.693 5.17 12.127 8.358c10.867 6.38 26.55 13.757 44.205 20.623c21.177 8.237 45.35 15.704 67.738 20.38v-27.61c-39.47-5.12-79.897-18.325-108.355-44.452zm298.71 0C376.897 402.055 336.47 415.26 297 420.38v27.61c22.387-4.676 46.56-12.143 67.738-20.38c17.655-6.865 33.338-14.243 44.205-20.622c5.434-3.19 9.674-6.17 12.127-8.36c1.127-1.004 1.52-1.797 1.73-2.16c-.482-4.675-3.027-9.97-7.163-14.105c-3.03-3.03-6.7-5.264-10.282-6.435zM77.322 410.602L18 450.15V494h37v-18h18v18h366v-18h18v18h37v-43.85l-59.322-39.548c-.537.488-1.08.97-1.623 1.457c-3.922 3.497-8.932 6.89-14.998 10.452c-12.133 7.12-28.45 14.743-46.795 21.877C334.572 458.656 290.25 471 256 471s-78.572-12.343-115.262-26.61c-18.345-7.135-34.662-14.757-46.795-21.878c-6.066-3.56-11.076-6.955-14.998-10.453c-.543-.487-1.086-.97-1.623-1.458zM233 422.184v28.992c8.236 1.162 16.012 1.824 23 1.824s14.764-.662 23-1.824v-28.992a325 325 0 0 1-46 0"></path></svg>

resources/resources.gresource.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<gresources>
+  <gresource prefix="/dev/moonarch/moonset">
+    <file>style.css</file>
+    <file>wallpaper.jpg</file>
+    <file>default-avatar.svg</file>
+  </gresource>
+</gresources>

resources/style.css

@@ -0,0 +1,105 @@
+/* ABOUTME: GTK4 CSS stylesheet for the Moonset power menu. */
+/* ABOUTME: Uses GTK theme colors for consistency with the active desktop theme. */
+
+/* Main panel window background */
+window.panel {
+    background-color: @theme_bg_color;
+    background-size: cover;
+    background-position: center;
+}
+
+/* Wallpaper-only window for secondary monitors */
+window.wallpaper {
+    background-color: @theme_bg_color;
+}
+
+/* Round avatar image */
+.avatar {
+    border-radius: 50%;
+    min-width: 128px;
+    min-height: 128px;
+    background-color: @theme_selected_bg_color;
+    border: 3px solid alpha(white, 0.3);
+}
+
+/* Username label */
+.username-label {
+    font-size: 24px;
+    font-weight: bold;
+    color: white;
+    margin-top: 12px;
+    margin-bottom: 40px;
+}
+
+/* Action button — square card */
+.action-button {
+    min-width: 120px;
+    min-height: 120px;
+    padding: 16px;
+    border-radius: 50%;
+    background-color: alpha(@theme_base_color, 0.55);
+    color: @theme_fg_color;
+    border: none;
+}
+
+.action-button:hover {
+    background-color: alpha(@theme_base_color, 0.7);
+}
+
+/* Action icon inside button — request 48px from theme, scale up via CSS */
+.action-icon {
+    color: @theme_fg_color;
+    -gtk-icon-size: 64px;
+}
+
+/* Action label below icon */
+.action-label {
+    font-size: 14px;
+    color: @theme_unfocused_fg_color;
+}
+
+/* Confirmation box below action buttons */
+.confirm-box {
+    padding: 16px 24px;
+    background-color: transparent;
+}
+
+/* Confirmation prompt text */
+.confirm-label {
+    font-size: 16px;
+    color: @theme_fg_color;
+    margin-bottom: 4px;
+}
+
+/* Confirm "Yes" button */
+.confirm-yes {
+    padding: 8px 24px;
+    border-radius: 8px;
+    background-color: @error_color;
+    color: @theme_bg_color;
+    border: none;
+    font-weight: bold;
+}
+
+.confirm-yes:hover {
+    background-color: lighter(@error_color);
+}
+
+/* Confirm "No/Cancel" button */
+.confirm-no {
+    padding: 8px 24px;
+    border-radius: 8px;
+    background-color: @theme_unfocused_bg_color;
+    color: @theme_fg_color;
+    border: none;
+}
+
+.confirm-no:hover {
+    background-color: @theme_selected_bg_color;
+}
+
+/* Error message label */
+.error-label {
+    color: @error_color;
+    font-size: 14px;
+}