feat: add summary dashboard history charts

Sources/Views/MainView.swift

@@ -8,6 +8,7 @@
 import SwiftUI
 import Combine
 import UserNotifications
+import SwiftData
 import AppKit
 import UniformTypeIdentifiers
 
@@ -37,9 +38,11 @@ struct MainView: View {
     @State private var draggedGroupID: UUID?
     @State private var groupDropIndicator: GroupDropIndicator?
     @State private var lastRefreshInterval: Int?
+    @State private var lastMetricPrune: Date?
     @State private var previousServiceStates: [String: String] = [:]
     private let serverOrderKey = MainView.serverOrderKeyStatic
     private let storedGroupsKey = MainView.storedGroupsKeyStatic
+    @Environment(\.modelContext) private var modelContext
 
     @State private var servers: [Server] = MainView.loadStoredServers()
     @State private var groups: [ServerGroup] = MainView.loadStoredGroups()
@@ -351,6 +354,7 @@ struct MainView: View {
                         var updated = servers[index]
                         updated.info = info
                         servers[index] = updated
+                        recordMetricSample(for: id, info: info)
                         checkServiceStatusChanges(for: server.hostname, newInfo: info)
                     }
                 }
@@ -386,6 +390,7 @@ struct MainView: View {
                     var updated = servers[index]
                     updated.info = info
                     servers[index] = updated
+                    recordMetricSample(for: id, info: info)
                 }
             }
         } catch {
@@ -451,6 +456,53 @@ struct MainView: View {
         }
     }
 
+    private func recordMetricSample(for serverID: UUID, info: ServerInfo) {
+        let sample = MetricSample(
+            serverID: serverID,
+            cpuPercent: info.load.percent,
+            memoryPercent: info.memory.percent,
+            swapPercent: info.swap.percent,
+            diskPercent: info.diskSpace.percent
+        )
+        modelContext.insert(sample)
+
+        do {
+            try modelContext.save()
+        } catch {
+            print("❌ [MainView] Failed to save metric sample: \(error)")
+        }
+
+        pruneOldMetricSamplesIfNeeded()
+    }
+
+    private func pruneOldMetricSamplesIfNeeded() {
+        let now = Date()
+
+        if let lastMetricPrune, now.timeIntervalSince(lastMetricPrune) < 3600 {
+            return
+        }
+
+        let cutoff = now.addingTimeInterval(-30 * 24 * 60 * 60)
+        let descriptor = FetchDescriptor<MetricSample>(
+            predicate: #Predicate { sample in
+                sample.timestamp < cutoff
+            }
+        )
+
+        do {
+            let expiredSamples = try modelContext.fetch(descriptor)
+            for sample in expiredSamples {
+                modelContext.delete(sample)
+            }
+            if !expiredSamples.isEmpty {
+                try modelContext.save()
+            }
+            lastMetricPrune = now
+        } catch {
+            print("❌ [MainView] Failed to prune metric samples: \(error)")
+        }
+    }
+
     private func deleteGroup(_ group: ServerGroup) {
         groups.removeAll { $0.id == group.id }
         for index in servers.indices {