feat(database): server_traffic table for per-minute traffic rollups

One row per server and minute (packets, bytes, resends, HTTP requests, errors,
bytes and latency percentiles), written in batches and read summed into
buckets for the longer chart ranges.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dDatabase/GameDatabase/ITables/IServerTraffic.h

@@ -0,0 +1,40 @@
+#ifndef __ISERVERTRAFFIC__H__
+#define __ISERVERTRAFFIC__H__
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+/**
+ * Per-minute traffic of each server (packets, bytes, HTTP requests), written by the dashboard once a minute from the
+ * servers' traffic reports and kept for traffic_days. The last hour at one second resolution is only in memory.
+ */
+class IServerTraffic {
+public:
+	struct TrafficMinute {
+		int64_t time{};       // start of the minute (or bucket), Unix seconds
+		std::string server;   // "master", "auth", "chat", "dashboard", "ugc", "world:<zone>:<instance>"
+		uint64_t packetsIn{};
+		uint64_t packetsOut{};
+		uint64_t bytesIn{};
+		uint64_t bytesOut{};
+		uint64_t resends{};
+		uint64_t httpRequests{};
+		uint64_t http4xx{};
+		uint64_t http5xx{};
+		uint64_t httpBytesOut{};
+		uint32_t latencyP50Us{}; // HTTP; in a bucket of several minutes: the average of the minutes'
+		uint32_t latencyP95Us{}; // in a bucket: the worst minute's
+		uint32_t latencyP99Us{}; // in a bucket: the worst minute's
+	};
+
+	// One batch a minute
+	virtual void InsertTrafficMinutes(const std::vector<TrafficMinute>& minutes) = 0;
+
+	// Rows between from and to (inclusive), summed per server into buckets of `bucketSeconds`, ordered by time
+	virtual std::vector<TrafficMinute> GetTrafficMinutes(int64_t from, int64_t to, int64_t bucketSeconds) = 0;
+
+	virtual uint32_t PruneTrafficMinutes(int64_t beforeTime) = 0;
+};
+
+#endif  //!__ISERVERTRAFFIC__H__