CREATE TABLE payment_proofs (
    id CHAR(36) PRIMARY KEY,
    order_id CHAR(36) NOT NULL,
    file_url VARCHAR(500) NOT NULL,
    uploaded_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    verified_by CHAR(36) DEFAULT NULL,
    verified_at TIMESTAMP NULL DEFAULT NULL,
    rejection_reason TEXT DEFAULT NULL,
    FOREIGN KEY (order_id) REFERENCES orders(id) ON DELETE CASCADE,
    INDEX idx_order_id (order_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;