Add report abuse, mute, ban and black mark systems

[HarleyGilpin]

Summary

Adds player moderation systems: abuse reports, mutes, bans and black marks.

• Report Abuse interface (594) opens from the chatbox Report button, right-clicking a player name in the chatbox, or a split private chat line; the client pre-fills the reported player's name
• Reports are queued and saved off the game thread with chat history evidence (last 20 messages / 5 minutes)
• Online moderators are notified of new reports and can request an immediate mute when reporting
• Mod commands: ::mute, ::permmute, ::unmute, ::ban, ::permban, ::unban, ::blackmark, ::blackmarks (work on offline players where applicable)
• Black marks expire after 12 months (permanent for real-world law offences); 10 active marks are required for permanent punishments
• Muted players are blocked from public, private and clan chat; banned players are rejected at login

Testing

• ReportAbuseTest covers report submission, validation, rate limiting, mod mute, and interface opening from the filter button, chatbox lines and private chat
• PunishmentsTest covers black mark accumulation, expiry and ban flags
• Verified in-game with the 634 client: right-click name → Report abuse opens the interface with the name pre-filled and the submitted report is saved

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