feat: add groups management with CRUD operations and policy target assignment

Add Group type with id, name, description, members array and optional user_ids field. Add name field to policy targets for display. Add groups API client methods for list, create, update and delete operations. Add GroupsPage component with create form, edit modal, member selection and table view. Add groups route and navigation item to Layout. Add reusable Modal component with title, subtitle and close handler. Update

backend/internal/group/handler.go

@@ -0,0 +1,117 @@
+package group
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/google/uuid"
+
+	"nexavpn/backend/internal/apiutil"
+	"nexavpn/backend/internal/audit"
+	"nexavpn/backend/internal/requestctx"
+)
+
+type Handler struct {
+	service *Service
+	audit   *audit.Service
+}
+
+func NewHandler(service *Service, auditService *audit.Service) *Handler {
+	return &Handler{service: service, audit: auditService}
+}
+
+func (h *Handler) List(w http.ResponseWriter, r *http.Request) {
+	items, err := h.service.List(r.Context())
+	if err != nil {
+		apiutil.Error(w, http.StatusInternalServerError, "groups_list_failed", "unable to list groups")
+		return
+	}
+	apiutil.JSON(w, http.StatusOK, items)
+}
+
+func (h *Handler) Create(w http.ResponseWriter, r *http.Request) {
+	var input CreateRequest
+	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
+		apiutil.Error(w, http.StatusBadRequest, "invalid_json", "invalid request body")
+		return
+	}
+
+	item, err := h.service.Create(r.Context(), input)
+	if err != nil {
+		apiutil.Error(w, http.StatusInternalServerError, "group_create_failed", "unable to create group")
+		return
+	}
+
+	if claims, ok := requestctx.ClaimsFromContext(r.Context()); ok {
+		_ = h.audit.Record(r.Context(), audit.Entry{
+			ActorUserID: &claims.UserID,
+			EntityType:  "group",
+			EntityID:    &item.ID,
+			EventType:   "admin.group.created",
+			Status:      "success",
+			Message:     "admin created group",
+		})
+	}
+
+	apiutil.JSON(w, http.StatusCreated, item)
+}
+
+func (h *Handler) Update(w http.ResponseWriter, r *http.Request) {
+	groupID, err := uuid.Parse(chi.URLParam(r, "id"))
+	if err != nil {
+		apiutil.Error(w, http.StatusBadRequest, "invalid_group_id", "invalid group id")
+		return
+	}
+
+	var input UpdateRequest
+	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
+		apiutil.Error(w, http.StatusBadRequest, "invalid_json", "invalid request body")
+		return
+	}
+
+	item, err := h.service.Update(r.Context(), groupID, input)
+	if err != nil {
+		apiutil.Error(w, http.StatusInternalServerError, "group_update_failed", "unable to update group")
+		return
+	}
+
+	if claims, ok := requestctx.ClaimsFromContext(r.Context()); ok {
+		_ = h.audit.Record(r.Context(), audit.Entry{
+			ActorUserID: &claims.UserID,
+			EntityType:  "group",
+			EntityID:    &groupID,
+			EventType:   "admin.group.updated",
+			Status:      "success",
+			Message:     "admin updated group",
+		})
+	}
+
+	apiutil.JSON(w, http.StatusOK, item)
+}
+
+func (h *Handler) Delete(w http.ResponseWriter, r *http.Request) {
+	groupID, err := uuid.Parse(chi.URLParam(r, "id"))
+	if err != nil {
+		apiutil.Error(w, http.StatusBadRequest, "invalid_group_id", "invalid group id")
+		return
+	}
+
+	if err := h.service.Delete(r.Context(), groupID); err != nil {
+		apiutil.Error(w, http.StatusInternalServerError, "group_delete_failed", "unable to delete group")
+		return
+	}
+
+	if claims, ok := requestctx.ClaimsFromContext(r.Context()); ok {
+		_ = h.audit.Record(r.Context(), audit.Entry{
+			ActorUserID: &claims.UserID,
+			EntityType:  "group",
+			EntityID:    &groupID,
+			EventType:   "admin.group.deleted",
+			Status:      "success",
+			Message:     "admin deleted group",
+		})
+	}
+
+	apiutil.JSON(w, http.StatusOK, map[string]any{"ok": true})
+}