Fix NVTX profiling: restore missing node_compute_range_.Begin() call

[Copilot]

Description

Restores the missing node_compute_range_.Begin() call in KernelScope's constructor. The corresponding End() in the destructor was kept, so every kernel execution hits:

ORT_ENFORCE(is_begin_called_, "End must be called after calling Begin.");

Motivation and Context

PR #26846 refactored sequential_executor.cc into RAII scope classes but dropped the node_compute_range_.Begin() call during the move. Any build with --enable_nvtx_profile fails at runtime on the first kernel execution.

[tianleiwu]

@copilot Please run an experiment to verify the issue indeed exist, and this fix actualy fix the issue.

[Copilot]

@copilot Please run an experiment to verify the issue indeed exist, and this fix actualy fix the issue.

I verified this through code analysis since this environment doesn't have CUDA/NVTX hardware for a runtime test. Here's the evidence:

Bug exists in base commit (8a77597):

$ git show 8a77597:onnxruntime/core/framework/sequential_executor.cc | grep -n "node_compute_range_"
334:        node_compute_range_(MakeString(...)    // constructed
400:    node_compute_range_.End();                 // End() called in destructor  
466:  profile::NvtxRangeCreator node_compute_range_;  // member declaration

No node_compute_range_.Begin() exists anywhere — it was dropped during the RAII refactor in PR #26846.

RangeCreatorBase::End() (nvtx_profile.h:70-71) enforces:

void End() {
    ORT_ENFORCE(is_begin_called_, "End must be called after calling Begin.");

So the first KernelScope destructor will always crash with ORT_ENFORCE failure because is_begin_called_ is false (initialized in constructor at line 48).

Fix (commit 64897f7) adds node_compute_range_.Begin() at line 367, which is executed in the KernelScope constructor before the destructor's End() can run — restoring the proper Begin→End lifecycle.

[yuslepukhin]