fix: resolve merge conflicts from role-based permissions + audit trail branches

Combines auth context keys (user role, IP, user-agent), tenant resolver
(GetUserRole-based access verification), middleware (deferred tenant
resolution + request info capture), and router (audit log + notifications
+ assignments).

backend/internal/handlers/deadlines.go

@@ -198,18 +198,8 @@ func (h *DeadlineHandlers) Delete(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-<<<<<<< HEAD
-	if err := h.deadlines.Delete(tenantID, deadlineID); err != nil {
+	if err := h.deadlines.Delete(r.Context(), tenantID, deadlineID); err != nil {
 		writeError(w, http.StatusNotFound, "deadline not found")
-||||||| 82878df
-	err = h.deadlines.Delete(tenantID, deadlineID)
-	if err != nil {
-		writeError(w, http.StatusNotFound, err.Error())
-=======
-	err = h.deadlines.Delete(r.Context(), tenantID, deadlineID)
-	if err != nil {
-		writeError(w, http.StatusNotFound, err.Error())
->>>>>>> mai/knuth/p0-audit-trail-append
 		return
 	}