Add read-only SnapTrade broker pack

[MasashiToda1]

Summary

• Add a signed SnapTrade Personal API read client and optional UTA broker pack.
• Surface a read-only SnapTrade preset for securities monitoring.
• Re-check connection status and require realtime/read/not-disabled before every account read.
• Permanently reject every order mutation before network I/O.

Scope

Initial position mapping is stock-like securities only: stocks, ETFs, ADRs, CEFs, and mutual funds. Unsupported derivatives, crypto, and cash-equivalents loud-refuse rather than being misclassified.

Validation

• SnapTrade broker test suite passed: 9 tests.
• TypeScript check passed.
• SnapTrade broker-pack build passed.

The repository-wide test command also ran. Existing environment-sensitive failures remain: local shellPath expectation, app-resource pack path, and UI localstorage/WebGL tests.

[vercel]

Someone is attempting to deploy a commit to the luokerenx4's Team Team on Vercel.

A member of the Team first needs to authorize it.

[RainMona]

云端代理审阅（以 upstream dev @ 47e8651b 为准）

结论

仍值得接，但需强制 rebase + 深度审核交易写路径。

现状

• SnapTrade 仍未进 dev；这是实体 Broker Pack / UTA adapter 工作，不是空 PR。
• 与 dev 有冲突；并且涉及交易写，按 workflow 应打 review:deep。
• Checks：Vercel 授权噪声；项目 CI 未见到结果。

建议

1. Rebase 到当前 dev（Broker Pack / UTA 路径一年多变化很大）。
2. 按 [docs/uta-live-testing.md] 走 paper 验收；不要用真金账户。
3. 确认与当前 Broker Pack 安装/激活模型一致（见 [docs/broker-packs.md]。
4. CI 绿 + deep review 后再合入。