feat: Yandex Metrika CID tracking, offline conversions UI, sticky pay button

- Pass yandex_cid to all auth endpoints (telegram, email, OIDC, OAuth)
- Add OfflineConvGoal interface and offline_conv_* fields to AnalyticsCounters
- Add storeYandexCid API method for server-side CID persistence
- Add analytics fields to LandingConfig (view/click goals, sticky_pay_button)
- Add yandex_cid/referrer/subid to PurchaseRequest
- Add offline conversions UI block in admin AnalyticsTab
- Add cacheYandexCid, syncYandexCid, fireAnalyticsEvent to analytics hook
- Create yandexCid.ts utility (localStorage get/set helpers)
- Add sticky pay button with portal on mobile in QuickPurchase
- Fire view/click analytics goals on landing pages
- Persist contact value and referrer/subid in session/localStorage
- Add i18n keys for offlineConv and apiKey in all 4 locales

src/hooks/useAnalyticsCounters.ts

@@ -1,6 +1,7 @@
 import { useEffect } from 'react';
 import { useQuery } from '@tanstack/react-query';
 import { brandingApi } from '../api/branding';
+import { setYandexCid } from '../utils/yandexCid';
 
 const YM_SCRIPT_ID = 'ym-counter-script';
 const GTAG_LOADER_ID = 'gtag-loader-script';
@@ -11,6 +12,11 @@ function removeElement(id: string) {
 }
 
 function injectYandexMetrika(counterId: string) {
+  try {
+    localStorage.setItem('ym_counter_id', counterId);
+  } catch {
+    /* sandboxed / private */
+  }
   if (document.getElementById(YM_SCRIPT_ID)) return;
 
   const script = document.createElement('script');
@@ -70,6 +76,8 @@ export function useAnalyticsCounters() {
     // Yandex Metrika
     if (data.yandex_metrika_id) {
       injectYandexMetrika(data.yandex_metrika_id);
+      cacheYandexCid(data.yandex_metrika_id);
+      syncYandexCid(data.yandex_metrika_id);
     } else {
       removeElement(YM_SCRIPT_ID);
     }
@@ -83,3 +91,87 @@ export function useAnalyticsCounters() {
     }
   }, [data]);
 }
+
+function cacheYandexCid(counterId: string) {
+  const w = window as unknown as Record<string, unknown>;
+  const ym = w.ym as ((...args: unknown[]) => void) | undefined;
+  if (typeof ym !== 'function') return;
+  setTimeout(() => {
+    try {
+      (w.ym as (...args: unknown[]) => void)(Number(counterId), 'getClientID', (cid: string) => {
+        if (cid) setYandexCid(cid);
+      });
+    } catch {
+      /* ignore */
+    }
+  }, 2000);
+}
+
+function syncYandexCid(counterId: string) {
+  const SENT_KEY = 'ym_cid_sent';
+  try {
+    if (localStorage.getItem(SENT_KEY)) return;
+  } catch {
+    return;
+  }
+  const w = window as unknown as Record<string, unknown>;
+  const ym = w.ym as ((...args: unknown[]) => void) | undefined;
+  if (typeof ym !== 'function') return;
+  setTimeout(() => {
+    try {
+      (w.ym as (...args: unknown[]) => void)(Number(counterId), 'getClientID', (cid: string) => {
+        if (!cid) return;
+        setYandexCid(cid);
+        // Only POST when the user is authenticated. Guest sessions cache the
+        // CID locally; it gets synced after login by the next mount of this
+        // hook on the cabinet shell.
+        let token: string | null = null;
+        try {
+          token = localStorage.getItem('access_token');
+        } catch {
+          /* ignore */
+        }
+        if (!token) return;
+        // Route through brandingApi (apiClient) so baseURL, auth refresh, and
+        // error handling all flow through the same interceptors as every other
+        // cabinet API call.
+        import('../api/branding').then(({ brandingApi: api }) => {
+          api
+            .storeYandexCid(cid)
+            .then(() => {
+              try {
+                localStorage.setItem(SENT_KEY, '1');
+              } catch {
+                /* ignore */
+              }
+            })
+            .catch(() => {
+              /* swallow -- non-critical, will retry on next login */
+            });
+        });
+      });
+    } catch {
+      /* ignore */
+    }
+  }, 3000);
+}
+
+export function fireAnalyticsEvent(goalName: string, params?: Record<string, unknown>) {
+  const w = window as unknown as Record<string, unknown>;
+  const ym = w.ym as ((...args: unknown[]) => void) | undefined;
+  if (typeof ym === 'function') {
+    try {
+      const counterId = localStorage.getItem('ym_counter_id');
+      if (counterId && /^\d{1,15}$/.test(counterId)) {
+        ym(Number(counterId), 'reachGoal', goalName, params);
+      }
+    } catch {
+      /* ignore */
+    }
+  }
+}
+
+// Re-export the canonical CID accessor from utils for back-compat with
+// existing imports inside this hook file. New code should import from
+// '../utils/yandexCid' directly to avoid pulling React into api/.
+export { getYandexCid } from '../utils/yandexCid';