feat(affiliate): 完善邀请返利系统

- 修复返利不到账的根因：tryClaimAffiliateRebateAudit 中 PostgreSQL 参数类型推断冲突
  - 补全 OAuth 注册路径（LinuxDo/OIDC/WeChat/Pending Flow）的邀请码绑定
  - 前端 OAuth 注册页面传递 aff_code 参数
  - 新增返利冻结期机制：可配置冻结时间，到期后自动解冻（懒解冻）
  - 新增返利有效期：绑定后 N 天内有效，过期不再产生返利
  - 新增单人返利上限：超出上限部分精确截断
  - 增强返利流程 slog 结构化日志，便于排查问题
  - 已邀请用户列表增加返利明细列

frontend/src/utils/__tests__/oauthAffiliate.spec.ts

@@ -0,0 +1,48 @@
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+import {
+  clearAffiliateReferralCode,
+  clearOAuthAffiliateCode,
+  loadAffiliateReferralCode,
+  loadOAuthAffiliateCode,
+  resolveAffiliateReferralCode,
+  storeAffiliateReferralCode,
+  storeOAuthAffiliateCode
+} from '@/utils/oauthAffiliate'
+
+describe('oauthAffiliate', () => {
+  beforeEach(() => {
+    localStorage.clear()
+    sessionStorage.clear()
+    vi.useRealTimers()
+  })
+
+  it('persists affiliate referral code across pages', () => {
+    expect(resolveAffiliateReferralCode(' 5579J7CFG9PF ')).toBe('5579J7CFG9PF')
+    expect(loadAffiliateReferralCode()).toBe('5579J7CFG9PF')
+    expect(resolveAffiliateReferralCode()).toBe('5579J7CFG9PF')
+  })
+
+  it('expires stale affiliate referral code', () => {
+    const now = Date.UTC(2026, 0, 1)
+    storeAffiliateReferralCode('AFF123', now)
+
+    expect(loadAffiliateReferralCode(now + 30 * 24 * 60 * 60 * 1000 - 1)).toBe('AFF123')
+    expect(loadAffiliateReferralCode(now + 30 * 24 * 60 * 60 * 1000 + 1)).toBe('')
+    expect(localStorage.getItem('affiliate_referral_code')).toBeNull()
+  })
+
+  it('keeps oauth transient code separate from persistent referral code', () => {
+    storeAffiliateReferralCode('PERSISTED')
+    storeOAuthAffiliateCode('OAUTH')
+
+    expect(loadAffiliateReferralCode()).toBe('PERSISTED')
+    expect(loadOAuthAffiliateCode()).toBe('OAUTH')
+
+    clearOAuthAffiliateCode()
+    expect(loadOAuthAffiliateCode()).toBe('')
+    expect(loadAffiliateReferralCode()).toBe('PERSISTED')
+
+    clearAffiliateReferralCode()
+    expect(loadAffiliateReferralCode()).toBe('')
+  })
+})

frontend/src/utils/oauthAffiliate.ts

@@ -0,0 +1,133 @@
+const OAUTH_AFFILIATE_CODE_KEY = 'oauth_aff_code'
+const AFFILIATE_REFERRAL_CODE_KEY = 'affiliate_referral_code'
+const AFFILIATE_REFERRAL_TTL_MS = 30 * 24 * 60 * 60 * 1000
+
+interface StoredAffiliateReferralCode {
+  code: string
+  expiresAt: number
+}
+
+export function normalizeOAuthAffiliateCode(value?: unknown): string {
+  const raw = Array.isArray(value) ? value[0] : value
+  return typeof raw === 'string' ? raw.trim() : ''
+}
+
+export function pickOAuthAffiliateCode(...values: unknown[]): string {
+  for (const value of values) {
+    const code = normalizeOAuthAffiliateCode(value)
+    if (code) {
+      return code
+    }
+  }
+  return ''
+}
+
+export function storeAffiliateReferralCode(value?: unknown, now = Date.now()): void {
+  if (typeof window === 'undefined') {
+    return
+  }
+  const code = normalizeOAuthAffiliateCode(value)
+  if (!code) {
+    return
+  }
+  try {
+    const payload: StoredAffiliateReferralCode = {
+      code,
+      expiresAt: now + AFFILIATE_REFERRAL_TTL_MS
+    }
+    window.localStorage.setItem(AFFILIATE_REFERRAL_CODE_KEY, JSON.stringify(payload))
+  } catch {
+    // 忽略浏览器存储异常。
+  }
+}
+
+export function loadAffiliateReferralCode(now = Date.now()): string {
+  if (typeof window === 'undefined') {
+    return ''
+  }
+  try {
+    const raw = window.localStorage.getItem(AFFILIATE_REFERRAL_CODE_KEY)
+    if (!raw) {
+      return ''
+    }
+    const parsed = JSON.parse(raw) as Partial<StoredAffiliateReferralCode>
+    const code = normalizeOAuthAffiliateCode(parsed.code)
+    const expiresAt = Number(parsed.expiresAt) || 0
+    if (!code || expiresAt <= now) {
+      clearAffiliateReferralCode()
+      return ''
+    }
+    return code
+  } catch {
+    clearAffiliateReferralCode()
+    return ''
+  }
+}
+
+export function clearAffiliateReferralCode(): void {
+  if (typeof window === 'undefined') {
+    return
+  }
+  try {
+    window.localStorage.removeItem(AFFILIATE_REFERRAL_CODE_KEY)
+  } catch {
+    // 忽略浏览器存储异常。
+  }
+}
+
+export function resolveAffiliateReferralCode(...values: unknown[]): string {
+  const code = pickOAuthAffiliateCode(...values)
+  if (code) {
+    storeAffiliateReferralCode(code)
+    return code
+  }
+  return loadAffiliateReferralCode()
+}
+
+export function storeOAuthAffiliateCode(value?: unknown): void {
+  if (typeof window === 'undefined') {
+    return
+  }
+  const code = normalizeOAuthAffiliateCode(value)
+  try {
+    if (code) {
+      window.sessionStorage.setItem(OAUTH_AFFILIATE_CODE_KEY, code)
+    } else {
+      window.sessionStorage.removeItem(OAUTH_AFFILIATE_CODE_KEY)
+    }
+  } catch {
+    // 忽略浏览器存储异常。
+  }
+}
+
+export function loadOAuthAffiliateCode(): string {
+  if (typeof window === 'undefined') {
+    return ''
+  }
+  try {
+    return normalizeOAuthAffiliateCode(window.sessionStorage.getItem(OAUTH_AFFILIATE_CODE_KEY))
+  } catch {
+    return ''
+  }
+}
+
+export function clearOAuthAffiliateCode(): void {
+  if (typeof window === 'undefined') {
+    return
+  }
+  try {
+    window.sessionStorage.removeItem(OAUTH_AFFILIATE_CODE_KEY)
+  } catch {
+    // 忽略浏览器存储异常。
+  }
+}
+
+export function clearAllAffiliateReferralCodes(): void {
+  clearOAuthAffiliateCode()
+  clearAffiliateReferralCode()
+}
+
+export function oauthAffiliatePayload(value?: unknown): { aff_code?: string } {
+  const code = normalizeOAuthAffiliateCode(value)
+  return code ? { aff_code: code } : {}
+}