agents: add runtime control for asset collection

Add comprehensive runtime control for asset collection (CPU/heap
profiling, snapshots) with multiple configuration methods.

Implements assetsEnabled flag with full control surface:
- NSOLID_ASSETS_ENABLED environment variable
- nsolid.start({ assetsEnabled: true/false }) configuration
- Runtime helpers: enableAssets() and disableAssets()
- Dynamic updates via gRPC reconfigure protocol
- Validation in both gRPC and ZMQ agents with proper errors
- Continuous profiler integration respects assetsEnabled state

This allows operators to disable expensive profiling operations
at runtime without process restarts, improving resource management
and production safety.

Also adds missing enableTraces()/disableTraces() helper methods
to complete the tracing API surface.

Comprehensive test coverage added for all asset types across gRPC,
ZMQ, and parallel test suites.

Author: santigimeno

agents/grpc/proto/reconfigure.proto

@@ -17,6 +17,7 @@ message ReconfigureBody {
   optional bool tracingEnabled = 10;
   optional uint32 tracingModulesBlacklist = 11;
   optional bool contCpuProfile = 12;
+  optional bool assetsEnabled = 13;
 }
 
 message ReconfigureEvent {

agents/grpc/src/grpc_agent.cc

@@ -392,6 +392,10 @@ void PopulateReconfigureEvent(grpcagent::ReconfigureEvent* reconfigure_event,
   if (it != config.end()) {
     body->set_contcpuprofile(*it);
   }
+  it = config.find("assetsEnabled");
+  if (it != config.end()) {
+    body->set_assetsenabled(*it);
+  }
 }
 
 void PopulateStartupTimesEvent(grpcagent::StartupTimesEvent* st_events,
@@ -440,6 +444,7 @@ GrpcAgent::GrpcAgent(): hooks_init_(false),
                         agent_id_(GetAgentId()),
                         auth_retries_(0),
                         unauthorized_(false),
+                        assets_enabled_(true),
                         profile_on_exit_(false) {
   ASSERT_EQ(0, uv_loop_init(&loop_));
   ASSERT_EQ(0, uv_cond_init(&start_cond_));
@@ -1186,12 +1191,12 @@ int GrpcAgent::config(const json& config) {
     ret = setup_metrics_timer(period);
   }
 
-    // uint64_t period = NSOLID_SPANS_FLUSH_INTERVAL;
-    // auto spans_flush_interval =
-    //   per_process::system_environment->Get(kNSOLID_SPANS_FLUSH_INTERVAL);
-    // if (spans_flush_interval.has_value()) {
-    //   period = std::stoull(spans_flush_interval.value());
-    // }
+  {
+    auto it = config_.find("assetsEnabled");
+    if (it != config_.end()) {
+      assets_enabled_ = *it;
+    }
+  }
 
   return ret;
 }
@@ -2084,6 +2089,11 @@ ErrorType GrpcAgent::do_start_prof_init(
     const grpcagent::CommandRequest& req,
     const ProfileType& type,
     ProfileOptions& options) {
+
+  if (!assets_enabled_) {
+    return ErrorType::EAssetsDisabled;
+  }
+
   const grpcagent::ProfileArgs& args = req.args().profile();
   uint64_t thread_id = args.thread_id();
   uint64_t duration = args.duration();

agents/grpc/src/grpc_agent.h

@@ -349,6 +349,7 @@ class GrpcAgent: public std::enable_shared_from_this<GrpcAgent>,
     log_exporter_;
 
   // Profiling
+  std::atomic<bool> assets_enabled_;
   nsuv::ns_mutex profile_state_lock_;
   ProfileState profile_state_[ProfileType::kNumberOfProfileTypes];
   std::atomic<bool> profile_on_exit_;

agents/grpc/src/grpc_errors.h

@@ -9,7 +9,8 @@
   X(ESnapshotDisabled, 500, "Heap Snapshots disabled", 1004)                   \
   X(ENoMemory, 500, "Internal Runtime Error", 1005)                            \
   X(ENotAvailable, 404, "Resource not available", 1006)                        \
-  X(ESourceCodeFileError, 500, "Internal Runtime Error", 1007)
+  X(ESourceCodeFileError, 500, "Internal Runtime Error", 1007)                 \
+  X(EAssetsDisabled, 500, "Assets collection disabled", 1008)
 
 namespace node {
 namespace nsolid {

agents/grpc/src/proto/reconfigure.pb.cc

@@ -1279,6 +1279,13 @@ int ZmqAgent::config(const json& config) {
     setup_blocked_loop_hooks();
   }
 
+  {
+    auto it = config_.find("assetsEnabled");
+    if (it != config_.end()) {
+      assets_enabled_ = *it;
+    }
+  }
+
   if (utils::find_any_fields_in_diff(diff, { "/app" })) {
     auto it = config_.find("app");
     if (it != config_.end()) {
@@ -2105,6 +2112,10 @@ void ZmqAgent::do_got_prof(ProfileType type,
 int ZmqAgent::do_start_prof_init(const nlohmann::json& message,
                                  ProfileType type,
                                  ProfileOptions& options) {
+  if (!assets_enabled_) {
+    return UV_EINVAL;
+  }
+
   StartProfiling start_profiling = nullptr;
   switch (type) {
     case ProfileType::kCpu: