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/config_test.go

@@ -0,0 +1,72 @@
+package handlers_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/user/nanometrics/server/db"
+	"github.com/user/nanometrics/server/handlers"
+	"github.com/user/nanometrics/server/models"
+)
+
+func testDB(t *testing.T) *db.DB {
+	d, _ := db.Open(":memory:")
+	t.Cleanup(func() { d.Close() })
+	return d
+}
+
+func TestServerConfigGetPut(t *testing.T) {
+	d := testDB(t)
+	h := handlers.ServerConfigHandler(d)
+
+	r := httptest.NewRequest(http.MethodGet, "/api/config", nil)
+	w := httptest.NewRecorder()
+	h(w, r)
+	if w.Code != 200 {
+		t.Fatalf("GET status: %d", w.Code)
+	}
+	var got models.ServerConfig
+	json.NewDecoder(w.Body).Decode(&got)
+	if got.TileMinWidth != 220 {
+		t.Errorf("tile_min_width défaut: %d", got.TileMinWidth)
+	}
+
+	cfg := models.DefaultServerConfig()
+	cfg.TileMinWidth = 300
+	body, _ := json.Marshal(cfg)
+	r2 := httptest.NewRequest(http.MethodPut, "/api/config", bytes.NewReader(body))
+	w2 := httptest.NewRecorder()
+	h(w2, r2)
+	if w2.Code != 204 {
+		t.Fatalf("PUT status: %d", w2.Code)
+	}
+
+	r3 := httptest.NewRequest(http.MethodGet, "/api/config", nil)
+	w3 := httptest.NewRecorder()
+	h(w3, r3)
+	var got2 models.ServerConfig
+	json.NewDecoder(w3.Body).Decode(&got2)
+	if got2.TileMinWidth != 300 {
+		t.Errorf("tile_min_width après PUT: %d", got2.TileMinWidth)
+	}
+}
+
+func TestAgentsHandler(t *testing.T) {
+	d := testDB(t)
+	h := handlers.AgentsHandler(d)
+
+	r := httptest.NewRequest(http.MethodGet, "/api/agents", nil)
+	w := httptest.NewRecorder()
+	h(w, r)
+	if w.Code != 200 {
+		t.Fatalf("status: %d", w.Code)
+	}
+	var agents []models.Agent
+	json.NewDecoder(w.Body).Decode(&agents)
+	if agents == nil {
+		// tableau vide attendu, pas d'erreur
+	}
+}