feat: integrate Stripe payment with subscription plans

Add Stripe payment integration across the project:

- Add @stripe/stripe-js dependency
- Configure Stripe environment variables (secret key, publishable key, webhook secret) for dev, local, and production environments
- Add Product/Price IDs for monthly, quarterly, and annual subscription tiers
- Extend subscription plan data with voiceMinutesPerDay quotas (30/45/60 minutes per tier)
- Update .gitignore to exclude implementation_plan.md

src/data/schemas/user/user.ts

@@ -17,12 +17,20 @@ export const UserSchema = z.object({
   personalityTraits: PersonalityTraitsSchema.default(PERSONALITY_TRAITS_DEFAULTS),
   preferredLanguage: z.string().default(""),
   createdAt: z.string().default(""),
-  // 后端**新**游客返回 null（"还没发过消息"），`.default("")` **不**兜 null —— 需 nullable
+  // 后端新游客返回 null（"还没发过消息"），`.default("")` 不兜 null —— 需 nullable
   lastMessageAt: z.string().nullable().default(null),
   avatarUrl: z.string().default(""),
   loginProvider: z.string().default("email"),
   isGuest: z.boolean().default(false),
+  /** 是否为 VIP 会员（订阅中或未过期） —— Stripe webhook 更新 */
+  isVip: z.boolean().default(false),
+  /** 语音聊天剩余分钟数（订阅生效后每天补充；用完为 0 不变） */
+  voiceMinutesRemaining: z.number().default(0),
+  /** Stripe Customer ID —— 首次 Checkout 完成后由 webhook 设置，用于 Customer Portal 自助管理 */
+  stripeCustomerId: z.string().nullable().default(null),
 });
 
+
+
 export type UserInput = z.input<typeof UserSchema>;
 export type UserData = z.output<typeof UserSchema>;