feat: add remote reboot support

Sources/Model/API/BaseAPI.swift

@@ -18,6 +18,7 @@ protocol ServerAPIProtocol {
     func fetchMemory() async throws -> MemoryType
     func fetchUtilization() async throws -> UtilizationType
     func fetchServerSummary(apiKey: String) async throws -> ServerInfo
+    func restartServer(apiKey: String) async throws
 }
 
 struct SystemInfo: Codable {
@@ -36,6 +37,15 @@ class BaseAPIClient {
     }
     
     func performRequest<T: Codable>(_ request: URLRequest, responseType: T.Type) async throws -> T {
+        let (data, _) = try await performDataRequest(request)
+        return try JSONDecoder().decode(T.self, from: data)
+    }
+
+    func performRequestWithoutBody(_ request: URLRequest) async throws {
+        _ = try await performDataRequest(request)
+    }
+
+    private func performDataRequest(_ request: URLRequest) async throws -> (Data, HTTPURLResponse) {
         let (data, response) = try await session.data(for: request)
         
         guard let httpResponse = response as? HTTPURLResponse else {
@@ -43,25 +53,61 @@ class BaseAPIClient {
         }
         
         guard 200...299 ~= httpResponse.statusCode else {
-            throw APIError.httpError(httpResponse.statusCode)
+            throw APIError.httpError(
+                httpResponse.statusCode,
+                BaseAPIClient.extractErrorMessage(from: data)
+            )
         }
         
-        return try JSONDecoder().decode(T.self, from: data)
+        return (data, httpResponse)
+    }
+
+    private static func extractErrorMessage(from data: Data) -> String? {
+        guard !data.isEmpty else { return nil }
+
+        if let envelope = try? JSONDecoder().decode(APIErrorEnvelope.self, from: data) {
+            let parts = [envelope.code, envelope.message]
+                .compactMap { $0?.trimmingCharacters(in: .whitespacesAndNewlines) }
+                .filter { !$0.isEmpty }
+
+            if !parts.isEmpty {
+                return parts.joined(separator: " ")
+            }
+        }
+
+        if let text = String(data: data, encoding: .utf8)?
+            .trimmingCharacters(in: .whitespacesAndNewlines),
+           !text.isEmpty {
+            return text
+        }
+
+        return nil
     }
 }
 
 enum APIError: Error, LocalizedError {
     case invalidURL
     case invalidResponse
-    case httpError(Int)
+    case httpError(Int, String?)
     case decodingError(Error)
+    case unsupportedFeature(String)
     
     var errorDescription: String? {
         switch self {
         case .invalidURL: return "Invalid URL"
         case .invalidResponse: return "Invalid response"
-        case .httpError(let code): return "HTTP Error: \(code)"
+        case .httpError(let code, let message):
+            if let message, !message.isEmpty {
+                return "HTTP Error: \(code)\n\(message)"
+            }
+            return "HTTP Error: \(code)"
         case .decodingError(let error): return "Decoding error: \(error.localizedDescription)"
+        case .unsupportedFeature(let feature): return "\(feature) is not supported by this host"
         }
     }
 }
+
+private struct APIErrorEnvelope: Decodable {
+    let code: String?
+    let message: String?
+}