feat(server): handlers REST + transport MQTT

Ajout des handlers HTTP (agents, métriques historique, config agent/serveur, icônes upload/get) et du client MQTT serveur avec subscribe automatique et PushConfig.

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

server/handlers/icons.go

@@ -0,0 +1,89 @@
+package handlers
+
+import (
+	"bytes"
+	"image"
+	_ "image/jpeg"
+	"image/png"
+	"net/http"
+	"strings"
+
+	"github.com/disintegration/imaging"
+	"github.com/user/nanometrics/server/db"
+)
+
+const maxIconSize = 128
+
+func IconUploadHandler(database *db.DB) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, "method not allowed", 405)
+			return
+		}
+		parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
+		if len(parts) < 4 {
+			http.Error(w, "invalid path", 400)
+			return
+		}
+		agentID := parts[2]
+
+		r.ParseMultipartForm(2 << 20)
+		file, header, err := r.FormFile("icon")
+		if err != nil {
+			http.Error(w, "fichier manquant", 400)
+			return
+		}
+		defer file.Close()
+
+		mime := header.Header.Get("Content-Type")
+		if mime == "" {
+			mime = "image/png"
+		}
+
+		if strings.Contains(mime, "svg") {
+			var buf bytes.Buffer
+			buf.ReadFrom(file)
+			if err := database.SaveIcon(agentID, buf.Bytes(), "image/svg+xml"); err != nil {
+				http.Error(w, err.Error(), 500)
+				return
+			}
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+
+		img, _, err := image.Decode(file)
+		if err != nil {
+			http.Error(w, "image invalide", 400)
+			return
+		}
+		resized := imaging.Fit(img, maxIconSize, maxIconSize, imaging.Lanczos)
+		var buf bytes.Buffer
+		if err := png.Encode(&buf, resized); err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+		if err := database.SaveIcon(agentID, buf.Bytes(), "image/png"); err != nil {
+			http.Error(w, err.Error(), 500)
+			return
+		}
+		w.WriteHeader(http.StatusNoContent)
+	}
+}
+
+func IconGetHandler(database *db.DB) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		parts := strings.Split(strings.Trim(r.URL.Path, "/"), "/")
+		if len(parts) < 4 {
+			http.Error(w, "invalid path", 400)
+			return
+		}
+		agentID := parts[2]
+		data, mime, err := database.GetIcon(agentID)
+		if err != nil {
+			http.Error(w, "not found", 404)
+			return
+		}
+		w.Header().Set("Content-Type", mime)
+		w.Write(data)
+	}
+}