💥 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/collector/collector.go

@@ -0,0 +1,37 @@
+package collector
+
+import (
+	"context"
+
+	"mfd-monitor-agent/internal/snapshot"
+	"mfd-monitor-agent/internal/status"
+)
+
+// namedCollector binds a stable collector name to a collection function.
+type namedCollector struct {
+	name string
+	fn   func(context.Context, *status.HostStatus) error
+}
+
+// Name returns the collector name used in snapshot error records.
+func (c namedCollector) Name() string {
+	return c.name
+}
+
+// Collect runs the wrapped collection function.
+func (c namedCollector) Collect(ctx context.Context, out *status.HostStatus) error {
+	return c.fn(ctx, out)
+}
+
+// New returns the default collector set for the current platform.
+func New(hostID string) []snapshot.Collector {
+	return []snapshot.Collector{
+		namedCollector{name: "system", fn: func(ctx context.Context, out *status.HostStatus) error {
+			return collectSystem(ctx, hostID, out)
+		}},
+		namedCollector{name: "network", fn: collectNetwork},
+		namedCollector{name: "resource", fn: collectResource},
+		namedCollector{name: "process", fn: collectProcesses},
+		namedCollector{name: "socket", fn: collectSockets},
+	}
+}