Closed Beta v3 zip shipped with the dev/ directory included

**Status: needs triage** (build process)

## Observation
The MultiplayerClosedBeta-v3.zip distribution of the API mod contains `dev/init.lua` (and its contents differ from the repo's version). The repo's release CI (`.github/workflows/strip-dev.yml`) strips `dev/` from release builds, so the beta zip appears to have been built from a working tree through a path that bypasses that step.

## Impact
Low today — `dev/init.lua` only enables env-var-driven dev auth, and the dev impersonation endpoint 404s against production servers. But it means beta testers are silently running dev-mode clients, and anything added to `dev/` in the future would ship to them unnoticed. Beta builds should go through the same strip step as releases (or include dev tooling deliberately as a documented decision).

从 .github/workflows/strip-dev.yml 开始，追踪 MultiplayerClosedBeta-v3.zip 的生成过程，查找绕过 strip 步骤的 beta 打包入口点。验证生成的归档内容；当 beta 构建始终排除 dev/，或 repository 记录了有意包含它的决定时，即表示完成。

由索引模型根据 Issue 内容生成。