Add SNS Marketing Campaign feature

- Add cash_cc_balance to User model (withdrawable CC)
- Create SnsShareSubmission model for SNS share verification
- Add marketing campaign settings to SystemSettings
- Add reward_type to ReferralReward model
- Create /api/sns-share endpoints for submission and verification
- Add referral signup reward logic (10CC on signup)
- Create /sns-share user page for SNS sharing
- Create /admin/sns-shares management page
- Add marketing settings UI to admin settings page
- Add SNS Shares menu to admin sidebar

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/lib/api.ts

@@ -1668,4 +1668,94 @@ export const visitorApi = {
   },
 };
 
+// SNS Share API
+export interface SnsShareSubmission {
+  id: number;
+  user_id: number;
+  car_id: number;
+  platform: string;
+  sns_url: string;
+  status: string;
+  rejected_reason?: string;
+  reward_cc: number;
+  rewarded_at?: string;
+  submitted_at: string;
+  verified_at?: string;
+  verified_by?: number;
+  car_name?: string;
+  car_image?: string;
+}
+
+export interface SnsShareListResponse {
+  submissions: SnsShareSubmission[];
+  total: number;
+  pending_count: number;
+  approved_count: number;
+  rejected_count: number;
+}
+
+export interface SnsShareStats {
+  total_submissions: number;
+  pending_submissions: number;
+  approved_submissions: number;
+  rejected_submissions: number;
+  total_rewarded_cc: number;
+}
+
+export interface CampaignStatus {
+  enabled: boolean;
+  start_date?: string;
+  end_date?: string;
+  sns_share_reward_cc?: number;
+  referral_signup_reward_cc?: number;
+  message?: string;
+}
+
+export const snsShareApi = {
+  // Public: 캠페인 상태 조회
+  getCampaignStatus: async (): Promise<CampaignStatus> => {
+    const { data } = await api.get('/sns-share/campaign-status');
+    return data;
+  },
+
+  // User: SNS 공유 URL 제출
+  submit: async (carId: number, platform: string, snsUrl: string): Promise<SnsShareSubmission> => {
+    const { data } = await api.post('/sns-share/submit', {
+      car_id: carId,
+      platform,
+      sns_url: snsUrl,
+    });
+    return data;
+  },
+
+  // User: 내 제출 목록 조회
+  getMySubmissions: async (): Promise<SnsShareListResponse> => {
+    const { data } = await api.get('/sns-share/my-submissions');
+    return data;
+  },
+
+  // Admin: 전체 제출 목록 조회
+  getAdminList: async (statusFilter?: string, skip: number = 0, limit: number = 50): Promise<SnsShareListResponse> => {
+    const params: any = { skip, limit };
+    if (statusFilter) params.status_filter = statusFilter;
+    const { data } = await api.get('/sns-share/admin/list', { params });
+    return data;
+  },
+
+  // Admin: 통계 조회
+  getAdminStats: async (): Promise<SnsShareStats> => {
+    const { data } = await api.get('/sns-share/admin/stats');
+    return data;
+  },
+
+  // Admin: 검증 (승인/거부)
+  verify: async (submissionId: number, approved: boolean, rejectedReason?: string): Promise<SnsShareSubmission> => {
+    const { data } = await api.put(`/sns-share/admin/${submissionId}/verify`, {
+      approved,
+      rejected_reason: rejectedReason,
+    });
+    return data;
+  },
+};
+
 export default api;