feat: add referral network graph visualization page

Interactive Sigma.js + graphology graph with ForceAtlas2 web worker
layout, campaign/user node coloring, filters via nodeReducer pattern,
search highlighting, user/campaign detail side panels, and 4-locale
translations. Dependencies: sigma v3, graphology, graphology-layout-forceatlas2.

src/types/referralNetwork.ts

@@ -0,0 +1,102 @@
+export interface NetworkUserNode {
+  id: number;
+  tg_id: number | null;
+  username: string | null;
+  email: string | null;
+  display_name: string;
+  is_partner: boolean;
+  referrer_id: number | null;
+  campaign_id: number | null;
+  direct_referrals: number;
+  total_branch_users: number;
+  branch_revenue_kopeks: number;
+  personal_revenue_kopeks: number;
+  personal_spent_kopeks: number;
+  subscription_name: string | null;
+  subscription_end: string | null;
+  registered_at: string | null;
+}
+
+export interface NetworkCampaignNode {
+  id: number;
+  name: string;
+  start_parameter: string;
+  is_active: boolean;
+  direct_users: number;
+  total_network_users: number;
+  total_revenue_kopeks: number;
+  conversion_rate: number;
+  avg_check_kopeks: number;
+  top_referrers: Array<{
+    user_id: number;
+    username: string | null;
+    referral_count: number;
+  }>;
+}
+
+export interface NetworkEdge {
+  source: string;
+  target: string;
+  type: 'referral' | 'campaign';
+}
+
+export interface NetworkGraphData {
+  users: NetworkUserNode[];
+  campaigns: NetworkCampaignNode[];
+  edges: NetworkEdge[];
+  total_users: number;
+  total_referrers: number;
+  total_campaigns: number;
+  total_earnings_kopeks: number;
+}
+
+export interface NetworkUserDetail {
+  id: number;
+  tg_id: number | null;
+  username: string | null;
+  email: string | null;
+  display_name: string;
+  is_partner: boolean;
+  referrer_id: number | null;
+  referrer_display_name: string | null;
+  campaign_id: number | null;
+  campaign_name: string | null;
+  direct_referrals: number;
+  total_branch_users: number;
+  branch_revenue_kopeks: number;
+  personal_revenue_kopeks: number;
+  personal_spent_kopeks: number;
+  subscription_name: string | null;
+  subscription_end: string | null;
+  registered_at: string | null;
+}
+
+export interface NetworkCampaignDetail {
+  id: number;
+  name: string;
+  start_parameter: string;
+  is_active: boolean;
+  direct_users: number;
+  total_network_users: number;
+  total_revenue_kopeks: number;
+  conversion_rate: number;
+  avg_check_kopeks: number;
+  top_referrers: Array<{
+    user_id: number;
+    username: string | null;
+    referral_count: number;
+  }>;
+}
+
+export interface NetworkSearchResult {
+  users: NetworkUserNode[];
+  campaigns: NetworkCampaignNode[];
+}
+
+export type SelectedNode = { type: 'user'; id: number } | { type: 'campaign'; id: number } | null;
+
+export interface NetworkFilters {
+  campaigns: number[];
+  partnersOnly: boolean;
+  minReferrals: number;
+}