feature: live community roster, recent players, community tab and public server leaderboards

[lukepolo]

Shows community server activity: a live roster and Recent Players for moderators, a Community tab on player pages, and a public stats page per server.

• Live roster from the plugin over a subscription, falling back to RCON polling only when the plugin isn't reporting
• One sanction pill per row, "Steam only" for players without an account, and shared IPs highlighted in the IP column
• Community tab after Combat: totals for everyone, plus exact sessions, names used and shared-IP accounts for moderators
• Public server page with a 7-day activity chart and This week / All time leaderboards by time or kills
• Retention setting for player sessions