维护者确认：#3575 开机启动与托盘启动选项

PR https://github.com/makecindy/cindy/pull/3575 需要维护者确认后再合并。

触发：
- product：feat + 设置页新增「开机启动 / 启动后进入托盘」选项（WindowBehaviorSection），用户看得见的设置与开机/托盘行为。
- security：改到 preload.ts 安全边界，这类不看 diff 大小、不按纯技术改动放过。
- arch：核心路径约 398 行（main / preload 等）。

请维护者直接在 PR 上 Approve 放行；若要改，请 Request Changes。不要只在本 issue 里口头说可以。

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关联 PR:#3575(作者 @YellowMark-Z);本 issue 由 review-pr 流程自动创建,用于先讨论该 PR 涉及的产品 / UI 变更,维护者确认后 PR 会恢复推进。

Start by reviewing PR #3575, focusing on WindowBehaviorSection and the preload.ts security boundary, then inspect the related main/preload startup and tray paths. Done means a maintainer has reviewed the product, UI, and security impact and either approves the PR or requests changes on the PR itself.

Written by the indexing model from the issue text.