Add Phase 4 edge case tests for LoopNode and Reactive nodes

New tests:
- gtest_loop.cpp: 15 tests for LoopNode decorator
  - Static queue parsing (int, double, string, bool)
  - Empty queue handling (if_empty parameter)
  - Dynamic queue from blackboard
  - Vector input conversion (Issue #969)
  - Child failure behavior
  - Restart after completion
  - convertFromString tests for SharedQueue types

- gtest_reactive.cpp: 7 additional tests
  - ReactiveSequence first child fails
  - ReactiveSequence halt on condition change
  - ReactiveFallback first child succeeds
  - ReactiveFallback all children fail
  - ReactiveSequence all children succeed
  - ReactiveSequence re-evaluates on every tick

Coverage improvements:
- loop_node.h: 65.9% -> 98.8% (+32.9%)
- reactive_fallback.cpp: 69.2% -> 74.4% (+5.2%)
- Overall: 76.6% -> 77.1%
- Tests: 420 -> 442 (+22)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

Author: facontidavide

tests/CMakeLists.txt

@@ -24,6 +24,7 @@ set(BT_TESTS
   gtest_name_validation.cpp
   gtest_json.cpp
   gtest_loggers.cpp
+  gtest_loop.cpp
   gtest_reactive.cpp
   gtest_reactive_backchaining.cpp
   gtest_sequence.cpp