feat(webui): add Install to Disk page

Expose the existing bee-install script through the web UI:
- platform/install.go: remove USB exclusion, add SizeBytes/MountedParts
  fields, add MinInstallBytes()/DiskWarnings() safety checks (size,
  mounted partitions, toram+low-RAM warning)
- webui: add GET /api/install/disks, POST /api/install/run,
  GET /api/install/stream endpoints
- webui: add Install to Disk page with disk table, warning badges,
  device-name confirmation gate, SSE progress terminal, reboot button

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

audit/internal/webui/api.go

@@ -409,6 +409,101 @@ func (h *handler) handleAPIPreflight(w http.ResponseWriter, r *http.Request) {
 	_, _ = w.Write(data)
 }
 
+// ── Install ───────────────────────────────────────────────────────────────────
+
+func (h *handler) handleAPIInstallDisks(w http.ResponseWriter, r *http.Request) {
+	if h.opts.App == nil {
+		writeError(w, http.StatusServiceUnavailable, "app not configured")
+		return
+	}
+	disks, err := h.opts.App.ListInstallDisks()
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	type diskJSON struct {
+		Device       string   `json:"device"`
+		Model        string   `json:"model"`
+		Size         string   `json:"size"`
+		SizeBytes    int64    `json:"size_bytes"`
+		MountedParts []string `json:"mounted_parts"`
+		Warnings     []string `json:"warnings"`
+	}
+	result := make([]diskJSON, 0, len(disks))
+	for _, d := range disks {
+		result = append(result, diskJSON{
+			Device:       d.Device,
+			Model:        d.Model,
+			Size:         d.Size,
+			SizeBytes:    d.SizeBytes,
+			MountedParts: d.MountedParts,
+			Warnings:     platform.DiskWarnings(d),
+		})
+	}
+	writeJSON(w, result)
+}
+
+func (h *handler) handleAPIInstallRun(w http.ResponseWriter, r *http.Request) {
+	if h.opts.App == nil {
+		writeError(w, http.StatusServiceUnavailable, "app not configured")
+		return
+	}
+	var req struct {
+		Device string `json:"device"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil || req.Device == "" {
+		writeError(w, http.StatusBadRequest, "device is required")
+		return
+	}
+
+	// Whitelist: only allow devices that ListInstallDisks() returns.
+	disks, err := h.opts.App.ListInstallDisks()
+	if err != nil {
+		writeError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	allowed := false
+	for _, d := range disks {
+		if d.Device == req.Device {
+			allowed = true
+			break
+		}
+	}
+	if !allowed {
+		writeError(w, http.StatusBadRequest, "device not in install candidate list")
+		return
+	}
+
+	h.installMu.Lock()
+	if h.installJob != nil && !h.installJob.isDone() {
+		h.installMu.Unlock()
+		writeError(w, http.StatusConflict, "install already running")
+		return
+	}
+	j := &jobState{}
+	h.installJob = j
+	h.installMu.Unlock()
+
+	logFile := platform.InstallLogPath(req.Device)
+	go runCmdJob(j, exec.CommandContext(r.Context(), "bee-install", req.Device, logFile))
+
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func (h *handler) handleAPIInstallStream(w http.ResponseWriter, r *http.Request) {
+	h.installMu.Lock()
+	j := h.installJob
+	h.installMu.Unlock()
+	if j == nil {
+		if !sseStart(w) {
+			return
+		}
+		sseWrite(w, "done", "")
+		return
+	}
+	streamJob(w, r, j)
+}
+
 // ── Metrics SSE ───────────────────────────────────────────────────────────────
 
 func (h *handler) handleAPIMetricsStream(w http.ResponseWriter, r *http.Request) {