feat(ui): ajout machine OS/type, section Hardware, identité app (tâche 3)

- AddMachineModal : sélecteurs OS + Type machine ; createMachine accepte
  osFamily/machineKind (manuel prioritaire, "Autre/auto" → détection os-release)
- section Hardware sur la tuile + panneau détail : os/type/virt/arch/gpu/réseau
  depuis machine_hardware (sonde) via GET /machines/:id/hardware
- identité : favicon.svg (serveur + LED Gruvbox), favicon.ico, apple-touch-icon,
  PWA 192/512, site.webmanifest ; liens + theme-color dans index.html

tsc 0 · 104 tests · build OK.

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

client/public/favicon.svg

@@ -0,0 +1,9 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 32 32" width="32" height="32" role="img" aria-label="System Update">
+  <rect x="1" y="1" width="30" height="30" rx="6" fill="#2a231d" stroke="#fe8019" stroke-width="2"/>
+  <rect x="7" y="8" width="18" height="6" rx="1.5" fill="none" stroke="#f2e5c7" stroke-width="1.6"/>
+  <circle cx="10" cy="11" r="1.3" fill="#4dbb26"/>
+  <line x1="14" y1="11" x2="22" y2="11" stroke="#d5c4a1" stroke-width="1.4" stroke-linecap="round"/>
+  <rect x="7" y="18" width="18" height="6" rx="1.5" fill="none" stroke="#f2e5c7" stroke-width="1.6"/>
+  <circle cx="10" cy="21" r="1.3" fill="#fe8019"/>
+  <line x1="14" y1="21" x2="22" y2="21" stroke="#d5c4a1" stroke-width="1.4" stroke-linecap="round"/>
+</svg>

client/public/site.webmanifest

@@ -0,0 +1,14 @@
+{
+  "name": "System Update",
+  "short_name": "SysUpdate",
+  "description": "Dashboard de mise à jour distante de machines Linux (SSH agentless).",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#2a231d",
+  "theme_color": "#fe8019",
+  "icons": [
+    { "src": "/favicon.svg", "type": "image/svg+xml", "sizes": "any", "purpose": "any" },
+    { "src": "/web-app-manifest-192x192.png", "type": "image/png", "sizes": "192x192", "purpose": "any maskable" },
+    { "src": "/web-app-manifest-512x512.png", "type": "image/png", "sizes": "512x512", "purpose": "any maskable" }
+  ]
+}