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>

backend/app/models/settings.py

@@ -47,6 +47,22 @@ class SystemSettings(Base):
     exchange_rate_weight_rub = Column(Float, default=0.0)  # RUB (러시아 루블) 가중치
     exchange_rate_weight_cny = Column(Float, default=0.0)  # CNY (중국 위안) 가중치
 
+    # 마케팅 캠페인 설정
+    marketing_enabled = Column(Boolean, default=False)  # 마케팅 캠페인 활성화
+    marketing_start_date = Column(DateTime(timezone=True), nullable=True)  # 캠페인 시작일
+    marketing_end_date = Column(DateTime(timezone=True), nullable=True)  # 캠페인 종료일
+
+    # SNS 공유 보상 설정
+    sns_share_reward_cc = Column(Float, default=3.0)  # SNS 공유 보상 CC (기본 3CC)
+    referral_signup_reward_cc = Column(Float, default=10.0)  # 레퍼럴 가입 보상 CC (기본 10CC)
+
+    # 이벤트 CC 유효기간 (개월)
+    event_cc_validity_months = Column(Integer, default=6)  # 이벤트 CC 유효기간 (기본 6개월)
+
+    # 출금 설정
+    withdrawal_enabled = Column(Boolean, default=True)  # 출금 기능 활성화
+    min_withdrawal_usd = Column(Float, default=10.0)  # 최소 출금 금액 (USD)
+
     # 타임스탬프
     created_at = Column(DateTime(timezone=True), server_default=func.now())
     updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())