feat(metrics): machine_metrics_simple — CPU/RAM/disque live par machine (tâche 4)

- template machine-metrics (loadavg/nproc, /proc/meminfo, df -B1) non destructif
- parseMetrics (TDD) → cpu load/cores, mémoire kB→B + %, filesystems, warnings >=90%
- collectMetrics (SSH léger) persiste machine_metrics_latest ; getLatestMetrics (sans SSH)
- routes GET /machines/:id/metrics + POST /metrics/collect ; api latestMetrics/collectMetrics
- section Hardware : bloc métriques live (CPU/RAM/disques + alertes) + bouton Collecter
  → comble le gap « Health » de la tâche 3

tsc 0 · 108 tests · build OK.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/services/machineMetrics.test.ts

@@ -0,0 +1,49 @@
+import { describe, it, expect } from "vitest";
+import { parseMetrics } from "./machineMetrics.js";
+
+const RAW = [
+  "===SU:METRICS_CPU===",
+  "0.08 0.12 0.09 1/234 5678",
+  "4",
+  "===SU:METRICS_MEM===",
+  "MemTotal:        4194304 kB",
+  "MemAvailable:    2097152 kB",
+  "===SU:METRICS_FS===",
+  "FS\t/\text4\t32000000000\t9280000000\t29%",
+  "FS\t/boot\text2\t500000000\t475000000\t95%",
+  "===SU:EXIT=0===",
+].join("\n");
+
+describe("parseMetrics", () => {
+  it("lit load average et cores", () => {
+    const m = parseMetrics(RAW);
+    expect(m.cpu.load1).toBe(0.08);
+    expect(m.cpu.load5).toBe(0.12);
+    expect(m.cpu.cores).toBe(4);
+  });
+
+  it("calcule la mémoire en octets (kB→B) et le pourcentage utilisé", () => {
+    const m = parseMetrics(RAW);
+    expect(m.memory.totalBytes).toBe(4194304 * 1024);
+    expect(m.memory.availableBytes).toBe(2097152 * 1024);
+    expect(m.memory.usedBytes).toBe((4194304 - 2097152) * 1024);
+    expect(m.memory.usedPercent).toBe(50);
+  });
+
+  it("liste les systèmes de fichiers", () => {
+    const m = parseMetrics(RAW);
+    expect(m.filesystems).toHaveLength(2);
+    expect(m.filesystems[0]).toEqual({
+      mount: "/",
+      fstype: "ext4",
+      sizeBytes: 32000000000,
+      usedBytes: 9280000000,
+      usedPercent: 29,
+    });
+  });
+
+  it("émet un warning pour un FS quasi plein (>=90%)", () => {
+    const m = parseMetrics(RAW);
+    expect(m.warnings.some((w) => w.includes("/boot"))).toBe(true);
+  });
+});