Merge upstream/main (Wei-Shaw/sub2api v0.1.121)

- 50 upstream commits since 2026-04-18 (VERSION 0.1.115 → 0.1.121)
- Conflicts resolved:
  * .gitignore: 保留我们的 superpowers/design-drafts 例外 + upstream 加的 ADMIN_PAYMENT_INTEGRATION_API.md
  * RegisterView.vue: 三段独立逻辑并存（password strength + match + upstream 的 validation toast + affiliate referral）
- Auto-merged 已验证保真度: router (PortalLayout + /pricing 5 处)、LoginView (narrative slot 20 处)、zh/en (5 个命名空间)
- typecheck + frontend build + backend go build 全部通过

主要 upstream 收益：
- backend: OpenAI/Anthropic/Codex/Vertex 等大量修复 + Anthropic 缓存 TTL 开关
- 3 个新 migration (131/132/133, affiliate)
- admin: ChannelMonitor 新页 + AccountsView 批量编辑 + SettingsView 大改
- user: AffiliateView/AvailableChannelsView/ChannelStatusView 新页 + Payment 流程改进
- auth: Wechat callback 新增

.gitignore

@@ -1,4 +1,5 @@
 docs/claude-relay-service/
+.codex
 
 # ===================
 # Go 后端
@@ -121,7 +122,7 @@ scripts
 .code-review-state
 #openspec/
 code-reviews/
-#AGENTS.md
+AGENTS.md
 backend/cmd/server/server
 deploy/docker-compose.override.yml
 .gocache/
@@ -131,10 +132,10 @@ docs/*
 !docs/PAYMENT_CN.md
 !docs/superpowers/
 !docs/design-drafts/
+!docs/ADMIN_PAYMENT_INTEGRATION_API.md
 .superpowers/
 .serena/
 .codex/
 frontend/coverage/
 aicodex
 output/
-