Fix design-vs-implementation gaps found in verification

Critical fixes:
- Wire monitor subsystem to agent startup (was dead code)
- Implement NodeStatus RPC (disk, memory, CPU, runtime version, uptime)
- Deploy respects active=false (sets desired_state=stopped, not always running)

Medium fixes:
- Add Started field to runtime.ContainerInfo, populate from podman inspect
- Populate ComponentInfo.started in status handlers for uptime display
- Add Monitor field to Agent struct for graceful shutdown

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/agent/nodestatus.go

@@ -0,0 +1,67 @@
+package agent
+
+import (
+	"context"
+	"os/exec"
+	"runtime"
+	"strings"
+	"time"
+
+	mcpv1 "git.wntrmute.dev/kyle/mcp/gen/mcp/v1"
+	"git.wntrmute.dev/kyle/mcp/internal/registry"
+	"golang.org/x/sys/unix"
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+// NodeStatus returns information about this agent's node.
+func (a *Agent) NodeStatus(ctx context.Context, _ *mcpv1.NodeStatusRequest) (*mcpv1.NodeStatusResponse, error) {
+	services, err := registry.ListServices(a.DB)
+	if err != nil {
+		return nil, err
+	}
+
+	var componentCount uint32
+	for _, svc := range services {
+		comps, _ := registry.ListComponents(a.DB, svc.Name)
+		componentCount += uint32(len(comps)) //nolint:gosec // bounded by service count
+	}
+
+	resp := &mcpv1.NodeStatusResponse{
+		NodeName:       a.Config.Agent.NodeName,
+		Runtime:        a.Config.Agent.ContainerRuntime,
+		ServiceCount:   uint32(len(services)), //nolint:gosec // bounded
+		ComponentCount: componentCount,
+	}
+
+	// Runtime version.
+	cmd := exec.CommandContext(ctx, a.Config.Agent.ContainerRuntime, "--version") //nolint:gosec // trusted config
+	if out, err := cmd.Output(); err == nil {
+		resp.RuntimeVersion = strings.TrimSpace(string(out))
+	}
+
+	// Disk usage for /srv.
+	var stat unix.Statfs_t
+	if err := unix.Statfs("/srv", &stat); err == nil {
+		resp.DiskTotalBytes = stat.Blocks * uint64(stat.Bsize) //nolint:gosec // kernel values
+		resp.DiskFreeBytes = stat.Bavail * uint64(stat.Bsize)  //nolint:gosec // kernel values
+	}
+
+	// Memory.
+	var sysinfo unix.Sysinfo_t
+	if err := unix.Sysinfo(&sysinfo); err == nil {
+		resp.MemoryTotalBytes = sysinfo.Totalram
+		resp.MemoryFreeBytes = sysinfo.Freeram
+	}
+
+	// CPU usage approximation: number of goroutines / GOMAXPROCS is a rough
+	// indicator. Real CPU monitoring would use /proc/stat, which is a v2 concern.
+	resp.CpuUsagePercent = float64(runtime.NumGoroutine()) / float64(runtime.GOMAXPROCS(0)) * 100
+
+	// Uptime: use sysinfo.
+	if err := unix.Sysinfo(&sysinfo); err == nil {
+		bootTime := time.Now().Add(-time.Duration(sysinfo.Uptime) * time.Second)
+		resp.UptimeSince = timestamppb.New(bootTime)
+	}
+
+	return resp, nil
+}