💥 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.go

@@ -0,0 +1,69 @@
+package httpapi
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"mfd-monitor-agent/internal/status"
+)
+
+// Provider supplies the latest cached HostStatus to HTTP handlers.
+type Provider interface {
+	// Get returns the latest snapshot and whether a snapshot is ready.
+	Get() (status.HostStatus, bool)
+}
+
+// StaticProvider is a test provider with a fixed snapshot response.
+type StaticProvider struct {
+	Snapshot status.HostStatus
+	OK       bool
+}
+
+// Get returns the configured static snapshot and readiness flag.
+func (p StaticProvider) Get() (status.HostStatus, bool) {
+	return p.Snapshot, p.OK
+}
+
+// New creates the HTTP API handler for health and status endpoints.
+func New(provider Provider) http.Handler {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		snapshot, ok := provider.Get()
+		if !ok {
+			writeJSON(w, http.StatusServiceUnavailable, map[string]any{
+				"status": "starting",
+			})
+			return
+		}
+		writeJSON(w, http.StatusOK, map[string]any{
+			"status":          "ok",
+			"version":         snapshot.Agent.Version,
+			"snapshot_at":     snapshot.Agent.SnapshotAt,
+			"snapshot_status": snapshot.Agent.SnapshotStatus,
+		})
+	})
+	mux.HandleFunc("/status", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		snapshot, ok := provider.Get()
+		if !ok {
+			http.Error(w, "snapshot not ready", http.StatusServiceUnavailable)
+			return
+		}
+		writeJSON(w, http.StatusOK, snapshot)
+	})
+	return mux
+}
+
+// writeJSON serializes value as JSON with a response status code.
+func writeJSON(w http.ResponseWriter, code int, value any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(code)
+	_ = json.NewEncoder(w).Encode(value)
+}