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).

Inizia da .github/workflows/strip-dev.yml e ricostruisci come è stato prodotto MultiplayerClosedBeta-v3.zip, cercando l’entry point del packaging della beta che ha bypassato il passaggio strip. Verifica il contenuto dell’archivio risultante; il lavoro è completato quando le build beta escludono costantemente dev/ oppure il repository documenta una decisione intenzionale di includerlo.

Scritto dal modello di indicizzazione a partire dal testo della issue.