Add Metrics tab with historical server utilization and map capacity

src/lib/server/db/schema.sql

@@ -560,3 +560,13 @@ BEGIN
         WHEN NEW.restart_state = 'manual' THEN 'Manual restart required'
         WHEN NEW.restart_state = 'held' THEN 'Changes held' ELSE NEW.restart_state END || CASE WHEN NEW.error IS NOT NULL THEN ' — ' || NEW.error ELSE '' END);
 END;
+-- Historical occupancy survives server removal; no player identities are stored.
+CREATE TABLE IF NOT EXISTS metric_samples (
+    at INTEGER NOT NULL,
+    server TEXT NOT NULL,
+    game TEXT NOT NULL,
+    map TEXT NOT NULL,
+    players INTEGER,
+    capacity INTEGER,
+    PRIMARY KEY (at, server)
+);