feat: add Prometheus and Grafana configurations and document Alpine Docker setup

monitoring/grafana/dashboard.json

@@ -0,0 +1,39 @@
+{
+  "title": "Linear Void Monitoring",
+  "panels": [
+    {
+      "title": "Concurrent Viewers",
+      "type": "timeseries",
+      "targets": [{ "expr": "linearvoid_chat_connected_clients" }]
+    },
+    {
+      "title": "Stored Messages",
+      "type": "stat",
+      "targets": [
+        {
+          "expr": "linearvoid_chat_messages_total"
+        }
+      ]
+    },
+    {
+      "title": "Moderation Actions",
+      "type": "timeseries",
+      "targets": [{ "expr": "linearvoid_chat_moderation_actions_total" }]
+    },
+    {
+      "title": "Redis Reachable",
+      "type": "stat",
+      "targets": [{ "expr": "linearvoid_chat_redis_up" }]
+    },
+    {
+      "title": "Admin Sessions",
+      "type": "timeseries",
+      "targets": [{ "expr": "linearvoid_chat_admin_sessions_active" }]
+    },
+    {
+      "title": "Chat Scrape Health",
+      "type": "stat",
+      "targets": [{ "expr": "up{job=\"chat\"}" }]
+    }
+  ]
+}