style: 优化按钮禁用态与主题入口并将设置移至侧栏底部

src/admin.css

@@ -12,7 +12,12 @@
     --app-accent: #07c160;
     --app-accent-hover: #2dcb79;
     --app-accent-text: #087c42;
-    --app-on-accent: #082b17;
+    --app-on-accent: #ffffff;
+    --app-button-primary: #078640;
+    --app-button-hover: #087c42;
+    --app-button-pressed: #066b36;
+    --app-disabled-bg: #e4e4e4;
+    --app-disabled-text: #8c8c8c;
     --app-selected: #e4f4e9;
     --app-shadow: #00000018;
     --app-danger: #a93232;
@@ -26,6 +31,8 @@
     --app-subtle: #232323;
     --app-control: #2b2b2b;
     --app-control-hover: #353535;
+    --app-disabled-bg: #303030;
+    --app-disabled-text: #808080;
     --app-border: #333333;
     --app-inverse: #111111;
     --app-accent-text: #5cd693;
@@ -65,6 +72,34 @@ body {
 .admin-sider {
     height: 100%;
 }
+/* 外壳固定品牌与底部设置；只有菜单自身使用 NScrollbar 滚动。 */
+.admin-sider-content {
+    display: flex;
+    flex-direction: column;
+    height: 100%;
+    min-height: 0;
+    overflow: hidden;
+}
+.admin-nav-scroll.n-scrollbar {
+    flex: 1;
+    min-height: 0;
+}
+.admin-sider-footer {
+    flex-shrink: 0;
+    padding-block: 8px max(8px, env(safe-area-inset-bottom));
+}
+.n-button.admin-settings-button {
+    justify-content: flex-start;
+    height: 44px;
+    padding-inline: 20px;
+}
+.n-button.admin-settings-button.is-collapsed {
+    justify-content: center;
+    padding-inline: 0;
+}
+.admin-settings-button.is-collapsed .n-button__icon {
+    margin: 0;
+}
 /* Naive 菜单背景默认左右内缩 8px；只铺满导航行，不改图标与文字缩进。 */
 .admin-sider .n-menu .n-menu-item-content::before {
     left: 0;
@@ -73,6 +108,7 @@ body {
 }
 .admin-brand {
     display: flex;
+    flex-shrink: 0;
     align-items: center;
     gap: 12px;
     height: 74px;
@@ -108,6 +144,10 @@ body {
 .n-button {
     border-radius: 0;
 }
+.n-button:focus-visible {
+    outline: 2px solid var(--app-accent-text);
+    outline-offset: 2px;
+}
 .admin-sider .n-menu-divider {
     height: 12px;
     background: transparent;
@@ -119,8 +159,10 @@ body {
 .workspace-tools-drawer .n-drawer-body {
     background: var(--app-body);
 }
-.theme-select {
-    width: 120px;
+.n-button.theme-toggle {
+    flex-shrink: 0;
+    width: 34px;
+    height: 34px;
 }
 .admin-content {
     flex: 1;
@@ -213,10 +255,6 @@ body {
     min-width: 180px;
     font-size: 12px;
 }
-.toolbar-episode > span {
-    flex-shrink: 0;
-    color: var(--app-muted);
-}
 .toolbar-episode .n-select {
     min-width: 0;
 }
@@ -1160,9 +1198,6 @@ body {
 .production-video {
     background: #080808;
 }
-.button-primary {
-    color: var(--app-on-accent);
-}
 .skip-link:focus {
     z-index: 3000;
 }
@@ -1185,6 +1220,7 @@ body {
         position: absolute;
         top: 44px;
         bottom: 0;
+        height: auto;
         z-index: 20;
         box-shadow: 6px 0 24px var(--app-shadow);
     }