feat(branding): force color mode (dark or light) site-wide

frontend/src/services/publicSettings.service.ts

@@ -19,6 +19,12 @@ export interface PublicSettings {
   branding_logo_display_header?: boolean;
   branding_logo_display_hero?: boolean;
   branding_hide_powered_by?: boolean;
+  /**
+   * Force the entire site into a specific color mode (instance-wide).
+   * 'dark' or 'light' override user/system preference; null = no force.
+   * AdminDarkModeContext + ThemeContext both honor this.
+   */
+  branding_force_color_mode?: 'dark' | 'light' | null;
   theme_config: any;
   default_language: string;
   enable_analytics: boolean;

frontend/src/services/settings.service.ts

@@ -19,6 +19,12 @@ export interface BrandingSettings {
   logo_display_hero?: boolean;
   logo_display_mode?: 'logo_only' | 'text_only' | 'logo_and_text';
   hide_powered_by?: boolean;
+  /**
+   * Force the entire admin and public site into a specific color mode.
+   * When set, the user-facing dark/light toggle is hidden and any per-theme
+   * `colorMode` override is ignored. `null` means no force (default behavior).
+   */
+  force_color_mode?: 'dark' | 'light' | null;
 }
 
 export interface ThemeSettings {
@@ -288,7 +294,12 @@ export const settingsService = {
       logo_display_header: this._parseBoolean(rawSettings.branding_logo_display_header, true),
       logo_display_hero: this._parseBoolean(rawSettings.branding_logo_display_hero, true),
       logo_display_mode: rawSettings.branding_logo_display_mode || 'logo_and_text',
-      hide_powered_by: this._parseBoolean(rawSettings.branding_hide_powered_by, false)
+      hide_powered_by: this._parseBoolean(rawSettings.branding_hide_powered_by, false),
+      force_color_mode: rawSettings.branding_force_color_mode === 'dark'
+        ? 'dark'
+        : rawSettings.branding_force_color_mode === 'light'
+          ? 'light'
+          : null
     };
   },