Fix fullPath() for nested behavior tree nodes

[zjn20030811]

Summary

• propagate each named control/decorator node into the prefix used while parsing its children
• make TreeNode::fullPath() identify the complete hierarchy for nested behavior-tree nodes
• add a regression test covering a nested Sequence/Fallback/leaf path

Fixes #1114.

Validation

• git diff --check
• Added SubTree.FullPathIncludesNodeHierarchy_Issue1114 regression coverage (CMake/gtest execution is unavailable in this Windows environment because no C++ compiler is installed).

[zjn20030811]

Validation update: the parser now carries each named control/decorator node into the child prefix, so nested fullPath() values are stable and human-readable. The new regression covers Sequence → Fallback → leaf hierarchy; git diff --check passes. A local CMake/gtest run is unavailable here because this Windows environment has no C++ compiler.

@facontidavide please review when convenient.

[zjn20030811]

CI follow-up: the new SubTree.FullPathIncludesNodeHierarchy_Issue1114 test passes in the Linux coverage and Ubuntu build jobs. Those jobs report four unrelated existing timing-sensitive failures (Parallel.FailingParallel, Parallel.ParallelAll, Reactive.TestLogging, and ReactiveBackchaining.EnsureWarm); the same set fails in both runs while all other 513 tests, including the regression, pass. Please consider a rerun when convenient.