feat(settings): per-theme visibility toggle (#2894)

Theme options gain an optional hidden flag in their JSON config. The
admin theme table gets a Visible checkbox per row; hidden themes are
filtered out of the user-facing theme picker and skipped by the
preferred-theme resolver so a hidden default or previously-selected
theme falls back cleanly.

Authored By: TDvorak <info@tdvorak.dev>

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

frontend/public/locales/en-US/dashboard.json

@@ -841,7 +841,8 @@
     "ssoRegisterEnabled": "Allow automatic registration",
     "ssoRegisterEnabledDes": "Automatically create a local account when a user signs in via SSO for the first time. The sign-up email filter below also applies.",
     "ssoCallbackUrl": "Callback URL",
-    "ssoCallbackUrlDes": "Register this URL as the redirect/callback URL in your identity provider: <0>{{url}}</0>"
+    "ssoCallbackUrlDes": "Register this URL as the redirect/callback URL in your identity provider: <0>{{url}}</0>",
+    "themeVisible": "Visible"
   },
   "giftCodes": {
     "giftCodesSettings": "Gift Codes",

frontend/public/locales/zh-CN/dashboard.json

@@ -841,7 +841,8 @@
     "ssoRegisterEnabled": "允许自动注册",
     "ssoRegisterEnabledDes": "用户首次通过 SSO 登录时自动创建本地账号。下方的注册邮箱过滤规则同样适用。",
     "ssoCallbackUrl": "回调地址",
-    "ssoCallbackUrlDes": "请在身份提供方中将此 URL 注册为 Redirect/Callback URL：<0>{{url}}</0>"
+    "ssoCallbackUrlDes": "请在身份提供方中将此 URL 注册为 Redirect/Callback URL：<0>{{url}}</0>",
+    "themeVisible": "可见"
   },
   "giftCodes": {
     "giftCodesSettings": "礼品码",

frontend/src/App.tsx

@@ -242,6 +242,7 @@ interface themeOptions {
 interface singleThemeOption {
   light: ThemeOptions;
   dark?: ThemeOptions;
+  hidden?: boolean;
 }
 
 const getPreferredTheme = (
@@ -250,16 +251,21 @@ const getPreferredTheme = (
   preferredTheme?: string,
   defaultTheme?: string,
 ): ThemeOptions => {
+  // Hidden themes are not user-selectable; fall back to the default when the
+  // preferred (or the last remaining) theme is hidden.
+  const visible = Object.values(opts).filter((o) => !o.hidden);
+  const pool = visible.length > 0 ? visible : Object.values(opts);
+
   let themeConfig = {} as singleThemeOption;
-  if (defaultTheme && opts[defaultTheme]) {
+  if (defaultTheme && opts[defaultTheme] && !opts[defaultTheme].hidden) {
     themeConfig = opts[defaultTheme];
   }
-  if (preferredTheme && opts[preferredTheme]) {
+  if (preferredTheme && opts[preferredTheme] && !opts[preferredTheme].hidden) {
     themeConfig = opts[preferredTheme];
   }
 
   if (!themeConfig?.light) {
-    themeConfig = Object.values(opts)[0];
+    themeConfig = pool[0];
   }
 
   if (mode === "dark" && themeConfig.dark) {

frontend/src/component/Admin/Settings/Appearance/ThemeOptions.tsx

@@ -36,6 +36,7 @@ export interface ThemeOptionsProps {
 interface ThemeOption {
   id: string;
   config: {
+    hidden?: boolean;
     light: {
       palette: {
         primary: {
@@ -234,6 +235,15 @@ const ThemeOptions = ({ value, onChange, defaultTheme, onDefaultThemeChange }: T
     [onDefaultThemeChange],
   );
 
+  const handleVisibilityChange = useCallback(
+    (id: string, visible: boolean) => {
+      const newOptions = { ...options };
+      newOptions[id] = { ...newOptions[id], hidden: !visible };
+      handleSave(newOptions);
+    },
+    [options, handleSave],
+  );
+
   const optionsArray = useMemo(() => {
     return Object.entries(options).map(([id, config]) => ({
       id,
@@ -256,6 +266,7 @@ const ThemeOptions = ({ value, onChange, defaultTheme, onDefaultThemeChange }: T
             <TableHead>
               <TableRow>
                 <NoWrapTableCell width={50}>{t("settings.defaultTheme")}</NoWrapTableCell>
+                <NoWrapTableCell width={50}>{t("settings.themeVisible")}</NoWrapTableCell>
                 <NoWrapTableCell width={150}>{t("settings.primaryColor")}</NoWrapTableCell>
                 <NoWrapTableCell width={150}>{t("settings.secondaryColor")}</NoWrapTableCell>
                 <NoWrapTableCell width={150}>{t("settings.primaryColorDark")}</NoWrapTableCell>
@@ -273,6 +284,13 @@ const ThemeOptions = ({ value, onChange, defaultTheme, onDefaultThemeChange }: T
                       onChange={() => handleDefaultThemeChange(option.id)}
                     />
                   </TableCell>
+                  <TableCell>
+                    <StyledCheckbox
+                      size="small"
+                      checked={!option.config.hidden}
+                      onChange={(e) => handleVisibilityChange(option.id, e.target.checked)}
+                    />
+                  </TableCell>
                   <TableCell>
                     <HexColorInput
                       required

frontend/src/component/Pages/Setting/PreferenceSetting.tsx

@@ -233,7 +233,9 @@ const PreferenceSetting = ({ setting, setSetting }: PreferenceSettingProps) => {
       </SettingForm>
       <SettingForm title={t("setting.themeColor")} lgWidth={12}>
         <SelectorBox sx={{ gap: 1 }}>
-          {Object.keys(themeOptions).map((color, index) => (
+          {Object.keys(themeOptions)
+            .filter((color) => !themeOptions[color]?.hidden)
+            .map((color, index) => (
               <ColorCircle
                 size={30}
                 color={color}