feat: store shard status in Redis

proto/discord.proto

@@ -0,0 +1,19 @@
+syntax = "proto3";
+
+message ShardState {
+    int32 shard_id = 1;
+    bool up = 2;
+    int32 disconnection_count = 3;
+
+    // milliseconds
+    int32 latency = 4;
+
+    // unix timestamp
+    int32 last_heartbeat = 5;
+    int32 last_connection = 6;
+}
+
+message GatewayEvent {
+    int32 shard_id = 1;
+    bytes payload = 2;
+}