feat(settings): Installation section

Server version + up-to-date/behind indicator via installation.info.

Outpost/Features/Account/SettingsView.swift

@@ -44,6 +44,9 @@ struct SettingsView: View {
     @State private var apiKeys: [OutlineAPIKey] = []
     @State private var isLoadingApiKeys = false
     @State private var apiKeysErrorMessage: String?
+    @State private var installationInfo: OutlineInstallationInfo?
+    @State private var isLoadingInstallationInfo = false
+    @State private var installationInfoErrorMessage: String?
 
     /// Full Local Sync and cache-clearing both need a real connection to be
     /// safe — clearing while offline (or letting Full Local Sync think it
@@ -87,6 +90,7 @@ struct SettingsView: View {
         case .notifications: notificationsDetail
         case .passkeys: passkeysDetail
         case .apiAccess: apiAccessDetail
+        case .installation: installationDetail
         case .offlineSync: offlineSyncDetail
         case .advanced: advancedDetail
         case .about: aboutDetail
@@ -820,6 +824,55 @@ struct SettingsView: View {
         }
     }
 
+    // MARK: - Installation
+
+    private var installationDetail: some View {
+        VStack(alignment: .leading, spacing: 16) {
+            sectionHeader
+
+            if isLoadingInstallationInfo && installationInfo == nil {
+                ProgressView().controlSize(.small)
+            } else if let installationInfoErrorMessage {
+                Text(installationInfoErrorMessage)
+                    .font(.caption)
+                    .foregroundStyle(.red)
+            } else if let installationInfo {
+                VStack(alignment: .leading, spacing: 6) {
+                    labeledRow("Version", installationInfo.version)
+                    Divider()
+                    if installationInfo.versionsBehind > 0 {
+                        labeledRow("Latest Version", installationInfo.latestVersion)
+                        Divider()
+                        Label(
+                            "\(installationInfo.versionsBehind) version\(installationInfo.versionsBehind == 1 ? "" : "s") behind",
+                            systemImage: "exclamationmark.triangle.fill"
+                        )
+                        .font(.caption)
+                        .foregroundStyle(.orange)
+                    } else {
+                        Label("Up to date", systemImage: "checkmark.circle.fill")
+                            .font(.caption)
+                            .foregroundStyle(.green)
+                    }
+                }
+                .frame(maxWidth: 420, alignment: .leading)
+            }
+        }
+        .task { await refreshInstallationInfo() }
+    }
+
+    private func refreshInstallationInfo() async {
+        guard let apiClient = session.apiClient else { return }
+        isLoadingInstallationInfo = true
+        defer { isLoadingInstallationInfo = false }
+        do {
+            installationInfo = try await apiClient.installationInfo()
+            installationInfoErrorMessage = nil
+        } catch {
+            installationInfoErrorMessage = outlineErrorMessage(error, fallback: "Couldn't load installation info.")
+        }
+    }
+
     // MARK: - Offline & Sync
 
     private var offlineSyncDetail: some View {