Add Traitors gameplay guide and bindable controls

[ywgATustcbbs]

Purpose / Summary

This change adds an in-game gameplay guide for the Traitors challenge. Every client can toggle it with the bindable I key while playing, dead, spectating, without a Marine, or after joining mid-game. The existing O skill-menu binding remains available and configurable.

Implementation

• C++ adds only the bindable command/input routing and the local rd_vgui_vscript input opt-in.
• Server VScript creates the per-player menu entity at gameplay start and on fullyjoined, then only notifies the client when the menu should open or close.
• Client VScript owns the home page, second-level page navigation, close/reset behavior, and ForceSync handling.
• Localization note: The English and Simplified Chinese localization text was written by a human.
• Long guide sections are split into shorter localized tokens and concatenated for display; tips remain as individual entries.

Safety / Lifecycle

• Menu entities are not created during briefing or mission selection, avoiding the debug UI assertion path that was previously exposed by early script startup.
• A local-player sentinel limits input control to the intended client.
• The guide does not depend on the client having a Marine, so dead and spectator clients remain eligible.

Testing and Review

• git diff --check passes.
• Static review covered the lifecycle, local-player routing, synchronization, localization fallback, and menu reset behavior.
• The test addon was manually tested for opening and closing the guide, navigating its pages, displaying text, and coexisting with the O skill menu binding.
• Spectator, dead-player, and late-join paths were reviewed line-by-line at code level; they were not claimed as manual gameplay tests here.

Development disclosure: This change was produced with AI assistance under human-authored instructions. The resulting code was reviewed line-by-line by a human and manually tested by a human.