💥 feat(agent)!: 添加主机监控代理首版

* 实现周期采集、快照缓存、本地 HTTP API 和主动上报

* 补齐 Linux 和 Windows 主机、网络、资源、进程和 TCP 采集

* 添加服务生命周期管理、配置加载、构建脚本和测试覆盖

BREAKING CHANGE: network.ips 拆分为 network.ipv4s 和 network.ipv6s。

internal/httpapi/server_test.go

@@ -0,0 +1,117 @@
+package httpapi
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"mfd-monitor-agent/internal/status"
+)
+
+// TestStatusReturnsCachedSnapshot verifies /status reads the provider cache.
+func TestStatusReturnsCachedSnapshot(t *testing.T) {
+	provider := StaticProvider{Snapshot: status.HostStatus{
+		Agent: status.AgentInfo{Version: "test", SnapshotAt: time.Now(), SnapshotStatus: "ok"},
+		Host:  status.HostInfo{Hostname: "host-a"},
+	}, OK: true}
+	server := New(provider)
+
+	req := httptest.NewRequest(http.MethodGet, "/status", nil)
+	rec := httptest.NewRecorder()
+	server.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status code = %d", rec.Code)
+	}
+	var got status.HostStatus
+	if err := json.NewDecoder(rec.Body).Decode(&got); err != nil {
+		t.Fatal(err)
+	}
+	if got.Host.Hostname != "host-a" {
+		t.Fatalf("hostname = %q", got.Host.Hostname)
+	}
+}
+
+// TestHealthReportsSnapshotMetadata verifies /health returns snapshot metadata.
+func TestHealthReportsSnapshotMetadata(t *testing.T) {
+	provider := StaticProvider{Snapshot: status.HostStatus{
+		Agent: status.AgentInfo{Version: "test", SnapshotAt: time.Unix(10, 0), SnapshotStatus: "partial"},
+	}, OK: true}
+	server := New(provider)
+
+	req := httptest.NewRequest(http.MethodGet, "/health", nil)
+	rec := httptest.NewRecorder()
+	server.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status code = %d", rec.Code)
+	}
+	var got map[string]any
+	if err := json.NewDecoder(rec.Body).Decode(&got); err != nil {
+		t.Fatal(err)
+	}
+	if got["snapshot_status"] != "partial" {
+		t.Fatalf("health = %+v", got)
+	}
+}
+
+// TestStatusReturnsServiceUnavailableBeforeSnapshot verifies /status does not live collect.
+func TestStatusReturnsServiceUnavailableBeforeSnapshot(t *testing.T) {
+	server := New(StaticProvider{OK: false})
+
+	req := httptest.NewRequest(http.MethodGet, "/status", nil)
+	rec := httptest.NewRecorder()
+	server.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusServiceUnavailable {
+		t.Fatalf("status code = %d", rec.Code)
+	}
+}
+
+// TestHealthReturnsStartingBeforeSnapshot verifies /health exposes startup state.
+func TestHealthReturnsStartingBeforeSnapshot(t *testing.T) {
+	server := New(StaticProvider{OK: false})
+
+	req := httptest.NewRequest(http.MethodGet, "/health", nil)
+	rec := httptest.NewRecorder()
+	server.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusServiceUnavailable {
+		t.Fatalf("status code = %d", rec.Code)
+	}
+	var got map[string]string
+	if err := json.NewDecoder(rec.Body).Decode(&got); err != nil {
+		t.Fatal(err)
+	}
+	if got["status"] != "starting" {
+		t.Fatalf("status = %q", got["status"])
+	}
+}
+
+// TestStatusRejectsNonGET verifies /status only accepts GET requests.
+func TestStatusRejectsNonGET(t *testing.T) {
+	server := New(StaticProvider{OK: true})
+
+	req := httptest.NewRequest(http.MethodPost, "/status", nil)
+	rec := httptest.NewRecorder()
+	server.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusMethodNotAllowed {
+		t.Fatalf("status code = %d", rec.Code)
+	}
+}
+
+// TestHealthRejectsNonGET verifies /health only accepts GET requests.
+func TestHealthRejectsNonGET(t *testing.T) {
+	server := New(StaticProvider{OK: true})
+
+	req := httptest.NewRequest(http.MethodPost, "/health", nil)
+	rec := httptest.NewRecorder()
+	server.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusMethodNotAllowed {
+		t.Fatalf("status code = %d", rec.Code)
+	}
+}