feat: add ButtonsTab for per-section button style customization

Visual editor in admin settings for configuring Telegram button colors
and custom emoji IDs per menu section. Includes API client, draft state
management, save/reset, and translations for ru/en/fa/zh locales.

src/api/buttonStyles.ts

@@ -0,0 +1,66 @@
+import apiClient from './client';
+
+export interface ButtonSectionConfig {
+  style: 'primary' | 'success' | 'danger';
+  icon_custom_emoji_id: string;
+}
+
+export interface ButtonStylesConfig {
+  home: ButtonSectionConfig;
+  subscription: ButtonSectionConfig;
+  balance: ButtonSectionConfig;
+  referral: ButtonSectionConfig;
+  support: ButtonSectionConfig;
+  info: ButtonSectionConfig;
+  admin: ButtonSectionConfig;
+}
+
+export type ButtonStylesUpdate = {
+  [K in keyof ButtonStylesConfig]?: Partial<ButtonSectionConfig>;
+};
+
+export const BUTTON_SECTIONS = [
+  'home',
+  'subscription',
+  'balance',
+  'referral',
+  'support',
+  'info',
+  'admin',
+] as const;
+
+export type ButtonSection = (typeof BUTTON_SECTIONS)[number];
+
+export const DEFAULT_BUTTON_STYLES: ButtonStylesConfig = {
+  home: { style: 'primary', icon_custom_emoji_id: '' },
+  subscription: { style: 'success', icon_custom_emoji_id: '' },
+  balance: { style: 'primary', icon_custom_emoji_id: '' },
+  referral: { style: 'success', icon_custom_emoji_id: '' },
+  support: { style: 'primary', icon_custom_emoji_id: '' },
+  info: { style: 'primary', icon_custom_emoji_id: '' },
+  admin: { style: 'danger', icon_custom_emoji_id: '' },
+};
+
+export const buttonStylesApi = {
+  getStyles: async (): Promise<ButtonStylesConfig> => {
+    try {
+      const response = await apiClient.get<ButtonStylesConfig>('/cabinet/admin/button-styles');
+      return response.data;
+    } catch {
+      return DEFAULT_BUTTON_STYLES;
+    }
+  },
+
+  updateStyles: async (update: ButtonStylesUpdate): Promise<ButtonStylesConfig> => {
+    const response = await apiClient.patch<ButtonStylesConfig>(
+      '/cabinet/admin/button-styles',
+      update,
+    );
+    return response.data;
+  },
+
+  resetStyles: async (): Promise<ButtonStylesConfig> => {
+    const response = await apiClient.post<ButtonStylesConfig>('/cabinet/admin/button-styles/reset');
+    return response.data;
+  },
+};